Ladies and gentlemen, thank you for standing by, and welcome to NetScout's fourth quarter and fiscal year 2019 results conference call. At this time, all parties are in listen-only mode until the question and answer portion of the call. As a reminder, this call is being recorded. Andrew Kramer, Vice President of Investor Relations, and his colleagues at NetScout are on the line with our 2020 guidance. Moving to slide number three, today's conference call will include forward-looking statements. These statements may be prefaced by words such as anticipate, believe, and expect, and will cover a range of topics that are not strictly historical facts, such as our financial guidance, our market opportunities and market share, key business initiatives, and future product plans, along with their potential impact on our financial performance.
These forward-looking statements involve risks and uncertainties, and actual results could differ materially from the forward-looking statements due to known and unknown risks, uncertainties, assumptions, and other factors which are described on the slide and in today's financial results press release, as well as in the company's annual report on Form 10-K and subsequent quarterly reports on Form 10-Q on file with the Securities and Exchange Commission. NetScout assumes no obligation to update any forward-looking information contained in this communication or with respect to the announcements described herein. Let's turn to slide four, which involves non-GAAP metrics. While this slide presentation includes both GAAP and non-GAAP results, unless otherwise stated, financial information discussed on today's conference call will be on a non-GAAP basis only. The rationale for providing non-GAAP measures, along with the limitations on relying solely on those measures, is detailed on the slide and in today's press release.
These measures should not be considered in isolation from, or as a substitute for, financial information prepared in accordance with GAAP. Additionally, as a result of the sale of the HNT Tools business, we will provide certain organic non-GAAP performance trends, which removes the HNT Tools revenue for comparability purposes. Reconciliations of all non-GAAP metrics with the applicable GAAP measure are provided in the appendix of the slide presentation in today's earnings press release, and they are also on our website. Our fiscal year 2019 fourth-quarter results were fundamentally consistent with the preliminary numbers that we shared with the market in early April. Despite lower-than-expected revenue, we delivered a relatively strong EPS performance due to higher gross margins, lower operating costs, and a lower-than-expected tax rate.
We believe that the combination of the progress we've made in the past year, along with our plans going forward, will help position the company to deliver better results in fiscal year 2020. I'll deliver the call over to Anil at this point, who will share his insights into what went well for NetScout last year and the opportunities and challenges that lie ahead.
Thank you, Andy. Good morning, everyone, and thank you for joining us. Let's begin on slide number six with a brief recap of our quarterly and full-year non-GAAP results. Today's results are fundamentally consistent with the preliminary results we reported in early April. Our fourth-quarter revenue of $235.2 million was approximately $15 million lower than we expected, primarily due to a delayed revenue recognition on the largest phase of service assurance project at an international mobile operator. Unfortunately, this customer's implementation schedule progressed slower than originally planned, and we are unable to backfill this given the ongoing spending challenges facing our service provider customers. Nevertheless, excluding the since-divested Handheld Network Test revenue from last year's fourth quarter, we generated overall organic revenue growth of 3%, driven by an 8% underlying increase in the enterprise customer segment, driven by strong growth in DDoS security and relatively stable service assurance revenue.
We successfully absorbed the top-line shortfall to deliver fourth-quarter diluted EPS of $0.66 due to higher gross margins, lower operating costs, and a lower tax rate. Despite falling short of our top-line ambitions in fiscal year 2019, with full-year revenue of $911.5 million, our diluted EPS of $1.38 was above the midpoint of our original target, due in part to the proactive initiatives we implemented to reduce costs and tightly manage spending earlier in the fiscal year. Overall, we made important progress during the past fiscal year on multiple fronts, which we believe will set the stage for generating better and more consistent results going forward. Let's move to slide seven for some further perspective into this. As you know, NetScout's top line has been negatively impacted over the last couple of years, largely as a result of reduced carrier spending, especially at our two largest tier 1 customers.
This dynamic was further compounded by integration complexity and adding disparate product lines that carried different pricing models, profitability levels, and value proposition. As we move forward, we believe that these severe headwinds have largely receded. At the same time, we are excited about our potential to benefit from new tailwinds related to our new product innovation in security and analytics and the continued migration to increasing software content. To summarize these dynamics, we have stabilized revenue from our two largest service provider customers in fiscal year 2019. We have successfully migrated most of our other tier 1 operators over the past two years to our software-based platform for service assurance.
Service provider-related revenue for the InfiniStreamNG software platform grew by nearly 40%, and it represented nearly 30% of our carrier-related service assurance product revenue last year. We have stabilized our DDoS revenue during the second half of the year, primarily due to improved enterprise traction. We have completed our R&D projects to integrate key products and technologies that were required as part of the Danaher Corporation Communications Business acquisition, and we have divested certain product lines that were unprofitable and had been in decline for multiple years. At the same time, we have made good progress on many other fronts, such as solid execution of our product strategy. We reshaped our product portfolio to focus on higher-margin, software-centric solutions. We broadened our range of solutions to provide visibility across any type of infrastructure into any service or applications.
We now provide greater deployment flexibility, ranging from appliances to software and virtual form factors. Our solutions address an expanded range of use cases from network application and infrastructure performance management to security and big data. We have begun to build sales momentum in our enterprise customer segment as customers start to move forward with digital transformation initiatives. We have reported three consecutive quarters of solid organic revenue growth in our enterprise customer segment. We completed the restructuring that began in the second quarter of last year. We expect that these actions will generate annual run rate saving of approximately $23 million, split between fiscal year 2019 and 2020. By restructuring key operations, selling non-core product lines, and carefully managing spending, we reduced operating costs by 9% in fiscal year 2019, and we believe that those actions will also help us keep costs relatively flat in the coming years.
Finally, we recently realigned leadership roles and the overall structure for our technical product delivery and sales organization in order to maximize our ability to accelerate key development initiatives and drive go-to-market effectiveness. Moving to slide eight. We believe that NetScout's focus on providing ultra-high-definition visibility into the real-time transactions embedded in network traffic is increasingly resonating with our customers who are challenged to efficiently and effectively transform and protect their infrastructure to support digital transformation without compromising their current capabilities. We recently held our annual technology and user summit, where we shared our product roadmap for the coming year, and the feedback from the customers, partners, and various industry analysts was very positive. As we move forward, we are focused on capitalizing on the following near and long-term opportunities to drive top-line growth.
In the enterprise, we see good scope for continuing to help our customers with their data center transformation initiatives, particularly as they migrate more of their application workloads to private and public cloud environments and improve overall agility. Security represents a promising adjacent as our value proposition expands beyond DDoS. We are looking to build on the early momentum we gained with the last year's launch of Arbor Edge Defense, which adds powerful new threat intelligence gateway capabilities to our proven set of enterprise DDoS capabilities. We plan to launch Arbor Threat Analytics within the next couple of months. This is a new enterprise security offering that takes advantage of NetScout's existing footprint inside our enterprise customers' network infrastructure.
This analytic platform combines our historical strength in packet forensics with Arbor's robust catalog of known security threats and new machine learning capabilities, thereby enabling security teams to work faster and more efficiently to identify and investigate potential network-based security breaches. Combining Arbor's sales resources with our large Service Assurance enterprise sales team was the final step in completing our integration efforts. With this behind us, we move forward with improved coverage, especially in certain international markets, and have strengthened our ability to maximize cross-selling opportunities across network and security operations. In our service provider customer segment, we continue to fortify our incumbency in Service Assurance, helping carriers add capacity to support growing traffic over their 4G networks, while also mining new opportunities for our nGenius business analytics and RAN optimization offering. Just as important, we are investing to support our customers as they advance their 5G network plans.
To unlock new DDoS opportunities with our carrier customers, we have continued enhancing our DDoS detection capabilities in ways that can help them improve the overall efficiency of their network security infrastructure. Let's turn to slide number nine, as I would like to focus on our outlook for fiscal year 2020 and offer some closing thoughts. We remain bullish on the opportunities we see and confident in our ability to capitalize on them. As we described, we believe that many of the issues that have limited our top-line results are behind us as we focus on maximizing the upside from a number of growth initiatives that are still in their early stages. As we move into fiscal year 2020, our top priority is to produce top-line growth, which is fundamental to driving operating leverage, EPS growth, and stronger free cash flow.
Our fiscal year 2020 plan is to generate low single-digit organic revenue growth through a mid-single-digit increase in product revenue growth, which is at the higher end of our plan can then be converted into mid-single-digit EPS growth. Looking more closely at our fiscal year 2022 revenue target that ranges from $895 million to $915 million, we have built our plan around the following assumptions. We expect our revenue growth will be driven by higher product revenue in our enterprise customer segment, as we see a good opportunity to sustain the organic growth we have generated in recent quarter. Although we are bullish on the long-term prospect of our new Arbor Threat Analytics, we anticipate relatively minimum contribution from this offering this year, given the early summer launch and conventional sales cycle.
We expect that the near-term service provider spending environment for both service assurance and DDoS security will remain difficult. While we expect 5G to be a catalyst for better spending over the longer term, this technology remains in its early phase. Nevertheless, we anticipate another good year in capturing 5G calibration deals, and we have recently won several initial deals for 5G radio access and network monitoring with tier 1 operators in North America. However, these carriers are moving cautiously to build out their 5G standalone architectures, which will ultimately require investment in new service assurance solutions.
In terms of diluted EPS guidance, we anticipate fiscal year 2022 diluted EPS in the range from $1.40 to $1.45, based on our plans for organic revenue growth, plus further gross margin improvement as the product mix continues to shift towards the software content, and basically flat operating expenses compared with last year's reporting of operating costs. That will enable us to deliver EPS growth even with an anticipated increase in our tax rate. Before I close my commentary, I wanted to provide a brief update on our change to our board of directors. Michael Szabados, who has made extensive contributions to NetScout's success in senior leadership roles, including the past 12 years as our COO, and Vivian Vitale, a highly respected and experienced HR leader with top technology companies, were appointed to our board earlier this year. Michael will serve as vice chairman of the board.
At the same time, Win Mullarkey, a long-standing NetScout director, retired, and I would like to thank Win for his service and support over the past two decades. Finally, I would like to thank my fellow Guardians around the world for their tireless efforts and dedication. I believe that we move forward having assembled a world-class experienced team that possesses unmatched domain expertise and is focused on the stellar execution of our plans this year. I look forward to sharing our continued progress and achievements with you over the course of the coming year and will turn the call over to Michael at this point.
Thank you, Anil. Good morning, everyone. Slide 11 outlines the areas I will cover. As Anil mentioned, we held our annual technology and user forum, ENGAGE, last month in Nashville. It was a resounding success with 700-plus attendees spanning our service provider, enterprise, government, and partner universe. Across both customer segments, digital transformation has become the common theme. We are well-positioned to help our customers reduce the risks and maximize the rewards of their highest impact digital transformation initiatives. That includes 5G, cloud, application performance, and security. I will intersperse some additional observations from ENGAGE as I cover several notable wins from the past quarter. In the service provider market, carrier marketing around 5G is increasing, although the infrastructure build-out and rollout of 5G services is moving at a more measured pace.
Our recent success with a tier 1 U.S. service provider demonstrates our potential to leverage our 4G incumbency to win new 5G-related projects and participate in all phases of the 5G network life cycle. In the fourth quarter, this carrier awarded us a mid-seven-figure deal to help calibrate the design of its 5G radio access network, or RAN. This long-standing customer is also starting to deploy our 5G-compatible RAN monitoring tools as they begin to launch new 5G-related services in limited markets. In the enterprise, a range of integrated offerings is enabling our enterprise customers to move forward with major data center transformation and multi-cloud migration strategies. To that end, we have continued to advance our relationships with major public cloud vendors like AWS and Microsoft Azure. NetScout is now an advanced technology partner at AWS, and we have recently achieved a co-sell-ready status with Microsoft Azure.
This enables us to actively collaborate with Microsoft sales teams to support customers who are migrating and managing applications in hybrid Azure environments. As customers seek greater visibility into application performance, our nGeniusPULSE offering is becoming increasingly valuable. Pulse is an active transaction testing tool that complements our core portfolio of passive monitoring solutions. It is gaining traction with customers who can use it to ensure basic connectivity, manage the availability, reliability, and performance of software-as-a-service or SaaS applications, and monitor infrastructure performance. We are seeing good interest in this product as indicated by our Pulse revenue nearly doubling last year off a very small base.
The product is almost always sold in tandem with our core products. The number of active trials continues to grow every quarter. During the fourth quarter, a long-standing financial services customer spent over a quarter of a million dollars on nGeniusPULSE to monitor connectivity at over 150 offices, data centers, and mission-critical call centers nationwide. This is just one part of a much larger deployment of NetScout technology that is helping the customer baseline existing dependencies, support evolving data center requirements, and deploy a new cloud platform. We see additional opportunities to further expand the scope of our management as this customer is actively evaluating Pulse's Wi-Fi monitoring capabilities. Turning to security, we are executing on our strategy to expand beyond DDoS.
At ENGAGE last month, we unveiled ATA, or Arbor Threat Analytics, a new enterprise security analytics software stack to detect and investigate potential security breaches using our ISNG and vSTREAM data sources. This new security product builds on our ability to support forensic use cases with our valuable packet data that can aid security teams as they seek to understand where and how they have been infiltrated. For example, last quarter, the cybersecurity organization at a large Midwest financial services firm selected NetScout to support a multi-phase project aimed at compliance with new state regulations that mandate the collection of forensic evidence for investigation into potential security breaches.
The new Arbor Threat Analytics is designed to make this even easier for customers like this customer to benefit through easy access to our IP packet recording at scale, a robust threat intelligence feed that can help quickly detect known threats that have already penetrated existing defenses, new capabilities that rapidly identify anomalous behavior on the network, and integration with third-party security information and event or SIEM platforms. I look forward to sharing additional news of our success in expanding our customer relationships in fiscal year 2020. That concludes my prepared remarks. At this point, I will turn the call over to Jean.
Thank you, Michael. Good morning, everyone. I plan to review key fourth quarter and full-year metrics along with our guidance for fiscal year 2020. As a reminder, this review focuses on our non-GAAP results unless otherwise stated. All reconciliations with our GAAP results appear in the presentation appendix. In addition, due to the sale of the HNT Tools business in mid-September, I will highlight certain revenue trends on an organic, non-GAAP basis, which removes HNT Tools revenue for the applicable period referenced. Regardless, I will be sure to note the nature of any such comparisons. Slide number 13 details our results for the fourth quarter and full fiscal year 2019. Focusing on the quarterly performance, we reported revenue of $235.2 million. Fourth quarter revenue declined by 1% on a year-over-year basis, but grew at 3% on an organic basis, excluding the HNT Tools business.
Revenue in the service provider customer segment was relatively flat, while our enterprise customer segment grew 8% organically. On a comparable organic basis, product revenue grew nearly 9%, and service revenue decreased 2%. Our fourth quarter of fiscal year 2019 gross margin was 79%, or a 2.3 percentage point increase from the same quarter last year, largely due to favorable product mix shifts. Quarterly operating expenses were down by 17% from the prior year due to lower personnel costs, primarily resulting from lower headcount. We reported an operating profit margin of 29.2% with diluted earnings per share of $0.66, which ended up higher than our April 9th estimate due to a lower than expected tax rate as we finalized our year-end numbers under the first full year of implementing the new tax code. As Anil mentioned, we completed our restructuring program during the fourth quarter.
We ended the fiscal year with 2,581 employees, which is a 14.5% reduction from a year ago. In fiscal year 2019, we saved a total of $10 million from our restructuring actions, which impacted our third and fourth fiscal quarters. For fiscal year 2020, we expect an additional $13 million in savings, which will impact our first and second quarters. This will result in a total run rate savings of about $23 million. In total, restructuring payments were approximately $17 million, and that is reflected in our free cash flow results for fiscal year 2019. There are no material restructuring payments associated with these programs anticipated in fiscal year 2020. Turning to slide 14, I'd like to review key revenue trends. Fiscal year 2019 revenue in the service provider customer segment declined by 13%, with service assurance down 10% and DDoS security down 20%.
In the enterprise segment, fiscal year 2019 revenue declined 4% due to the sale of the HNT Tools business. On an organic basis, enterprise revenue grew nearly 2% for the year. In terms of other full-year revenue trends, total revenue split between our enterprise and service provider customer segments. In terms of revenue by geography, which is calculated on a GAAP basis and includes revenue from the HNT Tools business, the U.S. experienced a 5% revenue decrease while international revenue declined by 12%. International customers represented 39% of GAAP revenue versus 41% last year. We had no customers who represented 10% or more of revenue in either the quarter or the year. Slide 15 details our balance sheet highlights and free cash flow.
We ended the quarter with cash equivalents, short-term marketable securities, and long-term marketable securities of $487 million, which is an increase of $11.2 million since the end of the third quarter. We generated free cash flow of $76.4 million for the quarter. In addition to repurchasing $14.5 million of our common stock in the quarter, we also repaid $50 million of the $600 million that was outstanding on our existing credit facility. For the full year, we generated free cash flow of just over $126 million, which includes the previously noted restructuring payments of $17 million. Excluding the restructuring payments, our free cash flow conversion was 131% of non-GAAP net income, and it was 116% conversion on the reported free cash flow. To briefly recap other balance sheet highlights, accounts receivable net were $235.3 million, up by $21.9 million at the end of the last fiscal year.
DSOs were 88 days versus 78 days at the end of FY 2018, and 91 days at the end of December. The increase from last year's level primarily reflects the timing of large maintenance renewals. I'd like to provide a brief update on our use of capital. Moving forward, we plan to retain up to $300 million in cash on our balance sheet at any given point for both working capital purposes and in consideration of overseas cash. In the near term, we plan to allocate up to $100 million for stock buyback and debt repayment. We anticipate being active in the market in the first quarter for share repurchases, depending on market conditions and subject to daily trading volumes and price considerations. Let's move to slide 16 for guidance. I will focus my review on our non-GAAP guidance.
As a reminder, we sold the HNT Tools business in September 2018, and it contributed $18 million to last year's revenue before the sale was completed. Accordingly, the impact of the divestiture should be taken into consideration when comparing fiscal years 2019 and 2020, especially for the first two quarters of both years. Slide 24 in the appendix details the HNT Tools' quarterly revenue contribution to last year's revenue. Consistent with Anil's comments earlier, we are currently targeting FY 2020 revenue in the range of $895 million to $915 million, which implies low single-digit organic growth. In terms of the other key FY 2020 operating model assumptions outlined on this slide, we currently anticipate further gross margin improvement as we drive adoption of our software solutions. Our plan currently calls for relatively flat operating costs compared with last year.
We anticipate that savings from last year's cost reduction actions will enable us to absorb incremental spending tied primarily to higher compensation costs associated with annual merit adjustments and critical personnel replacements, as well as additional investment in our enterprise security initiatives. We expect to deliver earnings growth despite an anticipated increase in our effective tax rate to between 23% and 25% as certain components of the new tax code are scheduled to increase. We are currently evaluating certain tax strategies that may enable us to keep the tax rate relatively flat with the prior year. Assuming 78.2 million shares outstanding, we currently expect diluted EPS between $1.40 and $1.45. I'd also like to offer some additional color on the first quarter. As a reminder, last year's first quarter revenue of $206 million included $10.4 million from the HNT Tools business.
As we assess the opportunities in front of us, we currently anticipate flat to 1% organic revenue growth, which equates to revenue in the range of $195 million to $200 million. We currently anticipate that around 46% of our expected annual revenue will come in the first half of the year. We are planning for modest gross margin improvement in the first quarter, with operating expenses in the range of 6%-7% lower than the same quarter one year ago. Diluted EPS for the first quarter is expected to range from $0.06 to $0.08. That concludes my formal review of our financial results. Before we transition to Q&A, I'd like to quickly note that our IR conference participation is listed on slide 17. I'll now turn the call over to the operator to start Q&A.
At this time, if you would like to ask a question, please press *1 on your touch-tone phone. If you wish to remove yourself from the queue, please press the # key. We do ask, in the interest of time, that you limit yourself to one question and one follow-up. We'll take our first question from Matt Hedberg with RBC Capital.
Hey guys. Thanks for the prepared remarks and the call here. In your prepared remarks, you outlined some of the assumptions of getting to low single-digit growth in fiscal 2020 here. I guess in the enterprise segment in particular, you noted contributions or I guess I'd say minimal contributions from some of the new Arbor threat products. Can you give us a little bit more granularity about when you think about this sustained enterprise growth, what are some of the key drivers that we should be watching as the year progresses on the enterprise side?
Matt, when we talked about the Arbor product, I just want to make sure there's no confusion between the previous product from Arbor Edge Defense, and other products in the DDoS area from the new product called Arbor Threat Analytics. Can you give us a little bit more granularity about when you think about this sustained enterprise growth, what are some of the key drivers that we should be watching as the year progresses on the enterprise side? Matt, when we talked about the Arbor product, I just want to make sure there's no confusion between the previous product from Arbor Edge Defense, and other products in the DDoS area from the new product called Arbor Threat Analytics. There is a good cross-selling potential as we have combined the two sales forces. Only about 10% of the NetScout enterprise customers use the Arbor DDoS and Arbor Edge Defense product. That's one area. Other is that in the data center transformation, our ability to allow people to get a single pane of glass, for before and after in the cloud, on-prem, server farm visibility is a new area which is generating a lot of interest.
Those are the two big reasons in the short term why we expect enterprise revenue growth, and we think there'll be sufficient growth overall as a result of that in the single digits, despite the fact there is going to be continued challenges on the service provider side, even though we think most of the challenges have bottomed out.
That's helpful. Maybe as a follow-up, Michael commented about advancements with AWS and Azure, and that kind of caught my attention. I know we've talked about this in the past for you guys, but maybe a little bit of an update about how that relationship or how those relationships, I should say, should not only help customers but also, how you think about that eventually impacting your growth.
We are now an APN member, which is an advanced partner network member with AWS, and that means that they can and do reference us in their working with their customers, in their migration projects. We are now part of the portfolio of vendors that AWS is publicly referencing as helpful or being part of a migration project. In the Microsoft case, being co-sell already means that Microsoft salespeople are quoted and are credited, that is paid on leads that involve NetScout. Also, any activity that either goes through Microsoft or even just registering a deal that involves NetScout is remunerative for them. These are material relationships. I expect that the symbolic nature of it and the fact that we get the credibility from these two top vendors, we are part of the technology platform to migrate.
I think that's where the real impact is going to come over the next year or two.
I think just to mention that one of the challenge of deploying on-prem, our solution is people's concern that what will happen if I move some of my application assets to Azure or AWS. Regardless of how much revenue we get directly from this relationship, that burden is taken away, and people don't have second thoughts on deploying our solution because they feel that it's going to be evergreen no matter where they run their application. These relationships, as Michael mentioned, sometime are just a check-off item and sometimes create confidence for people, and at other times, they've cut down the sales cycle because people don't have any fear that what's going to happen to their investment as they migrate their apps or workloads to the cloud.
Great. Thanks a lot, Matt.
Our next question comes from Chad Bennett with Craig-Hallum. Your line is open.
Great. Thanks for taking my questions. First, the Service Assurance product revenue. I think you indicated on the call that roughly 30% now is coming from software, and it grew roughly 40% year-over-year last year, which I think is good color. What are the expectations or embedded expectations for software growth in that segment this year? Obviously, if you answer that, we can figure out where it exits a year. Do you expect it to sustain that type of growth this year?
Yeah. This will continue, the goal in this area is to, over the next three-year period, to get to 70%, 80% of the revenue of service provider and some portion of the enterprise will come from software. Yeah, I think expect this trend to continue without maybe going over the exact number. Customers are deciding we have both the options, customer find a better price point for them, it's great for us because it's better margin for us. As a result, it's a win-win for both sides, that's why I think this trend will continue, may even accelerate.
Okay. Maybe one quick follow-up for me related to that. Your top two tier 1 customers on the service provider side that you indicated have stabilized now. Have you had any success in penetrating those two accounts with your software offering? Thanks.
Yeah. The software offering consists of two parts. One is the analytic applications, and other is the instrumentation. Instrumentation is vSTREAM, InfiniStreamNG. These two accounts have very high deployment of instrumentation, maybe to a saturation point on 4G. We have not made progress. They don't need anything from us. On the analytics side, yes, they are buying software. When they move to 5G, they'll have to use the software version, or they will prefer to use the software version. Last time, these two accounts are dominated by our Tektronix Communications products, which were all hardware-based. Because of that, we have not seen traction from them on the 4G side for using the software solutions.
We will take our next question from James Fish with Piper Jaffray.
Hey, guys. Thanks for the questions here. Just one quick one. Over the last few years, there's been some movements during the year, my first one would be: What could go right or wrong this year that would make you either exceed or miss your guidance, which would pretty much, over the next few quarters, make it so that NetScout hits their mark here as opposed to the last couple of years, where we've had some kind of adjustments mid-year on the initial guide?
Maybe I'll just mention some high-level thing, Alex, and maybe Jean can add to that commentary. I think the dynamics are different than in the last two years or last three years. We have heavy reliance on these two providers, and that, as I mentioned, largely bottomed out. We have more cushion on the margin side. We have reduced the cost structure. All that will provide some headroom. Also, if you notice, we are hoping that this year is less back-end loaded in the second half than we had last year. All those things reduces the risk. Unless there is some further change in the service provider segment of the market, which at this point we don't see, I think we feel good about the risk versus reward ratio this year.
Yeah, I would only add one thing to what Anil had said is, in his remarks, he had mentioned that one of the large opportunities that we have, that we've thought about for a few years now going forward, is the ability to cross-sell and to penetrate customers that are Arbor customers that don't use our product or that are legacy NetScout customers that don't use the Arbor product. That is the good news, and as that progresses and takes traction, that should be able to add a significant population to our revenue base. On the downside to that, obviously, that's something that is happening in the first quarter, depending on how fast the traction and the integration to the new territories works, you might be able to see some drag in the short term on that.
Got it. Thanks. Just one follow-up there. At what point, Anil, do we see service providers move from non-standalone mode to standalone mode for 5G? Actually, if I can sneak in one more. Jean, I didn't hear anything on the difference on the enterprise business between the security side and the service assurance. Can you give us the growth rates like you did for the service provider for that business as well? Thanks.
While Jean is looking at that, our instrumentation strategy is very similar for standalone versus non-standalone. For the current case, we will be using a lot of existing instrumentation. They will not need to do a wholesale upgrade because there are no new links. In the short term, the opportunity for 5G will be less. As they move to the standalone mode, there'll be additional places to put our technology at the edge. Our solution and architecture is sort of transparent to standalone versus non-standalone. If somebody has bought something for non-standalone on the existing links, they'll be using it for standalone or vice versa later on. I think that's a good story.
Because of these two cases, short-term opportunity for 5G is going to use a lot of the existing instrumentation, or at least on the data plane side, that will reduce the opportunity in the short term.
Hi, Jim, just to follow up on that question. In enterprise, the split between service assurance or the growth rates between service assurance and Arbor. In service assurance, the growth was a little less than 1%, and that is pro forma, as if the tools on an organic basis, as if the tools business had been in there on Q1 over Q1. In Arbor, they had a growth rate in the upper single digits. As we've talked about before, Arbor is a Cadillac product similar to NetScout's NPM products, and they do very well in very large, complex customers. In the fourth quarter, they were very successful in winning two large deployments in two very large financial institutions.
Thanks, Jean.
We can take our next question from Alex Kurtz with KeyBanc Capital Markets. Your line is open.
Thanks, and thanks for sneaking me in, guys. Just on the prepared remarks around the sales force restructuring or leadership changes, that's something that seems new to us. What was done exactly? How serious is it relative to changes that you've done in the past, and what areas would we expect to see changes? What verticals?
We have, on the product delivery side, the change is small, that there's a different leader on the Arbor side for the DDoS. Also, we have moved some of the security projects in other parts of the organization to use more resources, because we are using the same data for Arbor Threat Analytics as for nGeniusONE. The bigger change is on the sales side. We have a single worldwide leader for the sales force. Under that, there is a big leader on the international side, and multiple leaders on the U.S. side, sales leaders. At the account level, a single sales team is now supporting all product sales into that account. We tried some of those things last year, but there were a lot of sales conflicts with artificial quotas and things like that, and we didn't have a good impact on that.
We think to do cross-selling, to get the cross-selling advantages, which is either selling Arbor products to NetScout account or vice versa, we needed to do this integration. While it's going to be some disruption, but I think it's going to be more than made up by all the positives of the cross-selling arrangement, because as I mentioned, only if there is a 10% account overlap between the NetScout and Arbor customers.
Now, have there been leadership changes as far as personnel and reporting structure, or are these just changes at the account level and how accounts are covered?
Yeah, there are multiple changes at the reporting level. We have not hired people from outside. It's within the existing sales team there is movement and multiple reporting changes.
Okay. All right. Thank you.
We will take our next question from Eric Martinuzzi with Lake Street.
Yeah, I'd like to take a look backwards just on Q4, the delayed revenue recognition with the international service provider. Wondering if there were any lessons learned as a result of that shortfall, any workflow processes that were needed to be changed.
Yeah. First thing I wanted to mention, Eric, that a good portion of that revenue has already come in. Okay. I think the lesson learned there is that when it comes to Asia and sales cycle time, we have to be more conservative moving forward. These kind of things happen. There was a gap of just two weeks, nevertheless, it affected because it was the end of the year. I think that's the lesson learned in the sense that, a lot of non-product delays and paperwork and other things can extend the sales cycle time. The good news is that we'll be able to drive this revenue this year, and we already got part of it.
Okay. Speaking of the revenue this year, the question was previously asked, what puts you at the high end, what puts you at the low end? I wanted to frame it a little bit differently. Does getting to the high end of what you guys do, is that going to be probably driven more by enterprise outperformance? Or is it really going to be driven more by service provider maybe not being as pessimistic as you might have framed it with your stabilization commentary?
Well, both of them. It's outperformance versus last year on the enterprise side, and the negative impact of the service provider spending largely bottom out. The drag on the upside on enterprise is becoming less and less. At the same time, for shorter revenue, we have higher margin because of increased software content and the cost reduction exercises we went through last year.
As a reminder, if you would like to ask a question, please press star then one on your touch-tone phone. We will take our next question from Kevin Liu with K. Liu & Company. Your line is open.
Hi, good morning.
Good morning.
Just a follow on the software-only deals. Are you guys incentivizing your sales team any differently as you head into fiscal 2020, or are your customers just naturally opting for that more so as you make that push towards 70%-80% product coming from software?
Yeah. We are not incentivizing it, but we are allowing our sales force to give higher discounts and still get quota credit. There is a dynamic there that your flexibility of discounting to the customer on bigger deal sizes is better when you go with the software model. We have some things in place which allows us to control that.
Got it. Jean, last year, I think you provided some long-term targets coming into the fiscal year, calling for mid-single digit revenue growth over the longer term, low 30% operating margin, and maybe $3 in earnings over a four-year timeframe. Given some of the changes over the past year, are you guys still on track for that, or is there anything that should be updated in terms of either the expectations or the timing of when those are achieved?
On the earnings call a year ago, Anil had a slide that said, based on FY18, that by the end of fiscal year 2022, there would be about mid-single digit CAGR or better, that the gross margin would be in the low 80s, and that OPM would be in the low 30s. When you look at that, my thoughts are that gross margin is being driven by software only, which has a higher product margin, as well as considerable effect by flow-through on increased revenue. That would leave with the operating margins being at the low 30s. Today, the cost structure is such that there's probably some rationalization that still should occur to be able to hit those.
The interesting point that I find is if you look at the performance in Q4, where the gross margins have gotten close to 80% and the operating margins got close to 29%, and you annualize $235 million worth of revenue, you could see where those targets could still be relatively achievable by the end of FY 2022.
At this time, there are no additional questions. I'd like to turn the program back over to our presenters for any closing remarks.
Great. Well, I'd like to thank everybody for joining us this morning. We know it's a busy time. We appreciate you making time for NetScout. Look forward to seeing investors as we appear at different conferences throughout the quarter. If you have questions, please feel free to call me at the investor relations number, and we'll talk to you at some point as we move into the summer. Thank you.
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