All Other Telecommunications (NAICS 51781): An Investor's Primer

1. Overview

NAICS 51781 is a NAICS industry — a five-digit level in the North American Industry Classification System (NAICS), the code framework the U.S. Census Bureau uses to sort businesses [1]. At this level, "All Other Telecommunications" is the government's catch-all bucket for telecom firms that don't fit the big, familiar carrier categories: non-carrier voice and internet services (business "cloud phone" providers, dying dial-up) plus specialized radio-frequency and space-ground services (satellite tracking, telemetry, radar-station operation, and satellite earth stations, or "teleports") [1]. The unifying thread is that these firms do not operate as carriers over a network they own — so Verizon, AT&T, Comcast, and T-Mobile sit in adjacent codes, not here.

This is a single-child pass-through level. NAICS 51781 contains exactly one child industry — 517810, also named "All Other Telecommunications" — so the two are, for practical purposes, the same thing. Everything true of 517810 is true of 51781. This page gives the level's own ground-truth federal figures and the short version of the story; for full detail — segment economics, the company-by-company investable universe, regulation, and outlook — see the 517810 primer.

2. What's inside — and why this level equals its one child

The six-digit "national industry" is the finest layer of NAICS. When a five-digit industry has only one national industry beneath it, the two levels are definitionally identical — the parent is just the child under a shorter number [1]. That is the case here:

There is no aggregation happening — no sibling industries to sum, no blending of distinct businesses at the rollup. 51781's scope, its exclusions, its firm list, and its dollars are 517810's. (A naming note for research: in the prior 2017 NAICS vintage this industry was numbered 517919; the 2022 revision renumbered it, with essentially the same definition [1]. Older data may appear under 517919.)

3. How big it is

Using our ground-truth federal figures for this level (51781):

Our ground-truth file for 51781 carries receipts, firm count, and concentration only. Employment and payroll are not in it at this level; from the identical child industry (517810), County Business Patterns reports roughly 1,932 establishments, 26,776 paid employees, and $3.34 billion in annual payroll [3] — treat those as the same industry viewed one level down. The signature ratios stand out: revenue per employee near $790,000 and payroll only ~16% of receipts [2][3] — the mark of two low-labor models sitting together (capital-light resellers that pass carrier costs straight through, and capital-heavy antenna/teleport operators where hardware, not headcount, does the work).

The HHI of ~1,232 and CR4 of ~60% describe a moderately concentrated market: a handful of large operators hold most of the dollars, trailed by a long tail of tiny resellers and niche shops [2]. Because the code blends economically different businesses, read the HHI as a broad indicator, not a precise competition measure.

Undercount caveat — read before quoting the size. These federal figures are real but understate what a layperson would call "other telecom" [1][4]:

• Coverage by design. County Business Patterns excludes nonemployer (self-employed) businesses, and the Economic Census generally excludes government-owned establishments — this is an employer-business baseline, not the full footprint [4].
• Classification leakage. Many of the fastest-growing cloud-communications firms are coded as software (513210) or data processing (518210), so the biggest "internet phone" dollars sit outside this code [1].
• Invisible government activity. Much satellite tracking, telemetry, and radar-station work is done in-house by the Department of Defense (DoD), NASA, and NOAA, or by contractors coded elsewhere [4].

Treat the federal ~$21 billion as a floor for the establishment-based residual, not the industry's full economic footprint.

4. The investable universe — where value concentrates

Because 51781 equals 517810, the same value map applies, and there is no clean, code-pure public basket. Value concentrates in two very different places:

• Non-carrier voice/messaging (the public-market side, all small- or micro-cap): Bandwidth (BAND), 8x8 (EGHT), Ooma (OOMA), Crexendo (CXDO), IDT's net2phone unit (IDT), and Spok (SPOK) for clinical messaging [7][8][9][10][11][12]. These straddle NAICS lines — some revenue could be coded as software — so treat them as exposure to the theme, not an index of the code.
• Specialized space-ground and radio-frequency services (overwhelmingly private): Ground-Station-as-a-Service (GSaaS) and teleport operators such as KSAT, ATLAS Space Operations, RBC Signals, and Leaf Space; hyperscaler ground networks (AWS Ground Station, Azure Orbital) buried inside mega-caps; and government tracking/telemetry/radar work scattered across defense-IT contractors (Peraton, Leidos, SAIC) [24]. This is the part that genuinely sits in the code's "space" definition, and it is largely a private-market and defense-contractor story, not a listed one.

See the 517810 primer for the full company tables, market values, and the adjacent satellite operators (Iridium, Globalstar, Viasat, EchoStar, AST SpaceMobile — mostly the separate 517410 code) used as thematic proxies.

5. How the money works

Two distinct models, unchanged from the child level:

• Model A — Non-carrier voice/messaging (asset-light, subscription). Firms sell seats and usage riding on the customer's broadband, so economics look like software: recurring revenue = subscribers × average revenue per user (ARPU), tracked as monthly/annual recurring revenue (MRR/ARR), with churn, net revenue retention, and customer-acquisition cost as the health metrics. Gross margins run ~60–75%, dented by call-termination fees, number costs, and telecom taxes. The winning motion is "land and expand" — grow seats and add-ons (video, contact center, AI) faster than headcount.
• Model B — Teleports, GSaaS, and government RF services (asset-heavy or contract-based). Ground-station operators sell antenna time priced per "pass" (one overhead satellite contact), per minute, or as capacity; because the cost base is fixed, utilization is everything and a globally dispersed footprint (especially polar sites) is pricing power [24]. Government tracking/telemetry/radar contracts are backlog-driven, lower-margin, but sticky and recession-resistant.

The blended figures for the whole code — high revenue per head, low payroll share — are exactly this barbell [2][3]. The federal file provides no industry-wide utilization, margin, capex, or growth series, so those must be underwritten company by company.

6. What drives demand

• Voice/messaging: the shift of business phone systems from on-premises hardware and legacy copper ("plain-old-telephone-service," POTS) to cloud calling; hybrid work; AI features (call transcription, virtual agents) lifting revenue per seat; and Internet-of-Things (IoT) and secure healthcare/public-safety messaging [7][12].
• Space-ground: the low-Earth-orbit (LEO) satellite boom — mega-constellations mean thousands of fast-moving satellites, each needing frequent telemetry, tracking, and command (TT&C) contacts and data downlinks, which requires many globally spread antennas [18][19]. Forecasters expect the broader satellite-ground market to roughly double, ~$41 billion (2025) to ~$83 billion (2030), with GSaaS growing faster off a small base — a demand backdrop, not the size of this code [18][19].

7. Regulation

Regulation tracks the two segments and is identical to 517810's. In brief: the Federal Communications Commission (FCC) regulates nonfederal spectrum; the National Telecommunications and Information Administration (NTIA) manages federal spectrum [23]. Interconnected Voice over Internet Protocol (VoIP) carries FCC obligations — Enhanced 911 (E911), Universal Service Fund (USF) contributions, STIR/SHAKEN caller-ID authentication (a 2025 deadline broadened who must comply), CALEA lawful-intercept, and telecom taxes — a real drag on otherwise software-like margins [20]. Satellite-ground requires FCC Part 25 earth-station licensing, plus export controls (ITAR/EAR) on TT&C ground stations and CFIUS review of sensitive foreign investment [21][22][24]. Full detail is in the 517810 primer.

8. Consolidation

Because the level is its one child, the same dynamics apply: voice/messaging is brutally competitive and commoditizing — standalone cloud-phone providers are squeezed between Microsoft Teams Phone and Zoom bundling calling into products customers already own, driving consolidation and pushing survivors toward AI-differentiated voice [9]. The ground segment is consolidating around scale and cloud, with KSAT's global antenna footprint leading and hyperscalers entering [24]. Reported deals include Ericsson's $6.2 billion Vonage purchase (2022), Ooma's FluentStream and Phone.com buys (2025), 26North's acquisition of Intermedia (2026), and Rocket Lab's agreement to acquire Iridium (reported to close ~2027) [19][7][20][23]. Concentration (CR4 ~60%, HHI ~1,232) confirms a few large operators on the dollars and a long tail on the firm count [2].

9. Risks

Same risks as the child industry: commoditization and big-tech bundling on the voice side; heavy regulatory/tax burden (E911, USF, STIR/SHAKEN, CALEA); legacy decline of dial-up, paging, and low-end voice; hyperscaler competition and lumpy capital intensity on the ground side; customer and geopolitical concentration in government RF work (defense/NASA/NOAA budgets, export-control and CFIUS exposure); third-party dependency on carriers and data centers; technology obsolescence; private-equity leverage in roll-ups; and analytical opacity — as a residual code with classification leakage and understated nonemployer/government activity, the sector is genuinely hard to size and benchmark [1][4].

10. How to invest and the outlook

Routes in. Public-market exposure is a set of small-cap cloud-phone/messaging names (BAND, EGHT, OOMA, CXDO, IDT, SPOK) plus larger adjacent-code proxies (RingCentral, Zoom, Twilio for cloud communications; satellite operators for the space theme) [7][8][9][13][14]. The satellite-ground growth story is largely private — venture and private-equity stakes in GSaaS and teleport operators, and government-contract vehicles serving DoD/NASA/NOAA [24]. Start from segment exposure, not the NAICS label.

Outlook. 51781 is a two-speed industry on a mature base: the voice side turns on whether AI features lift revenue per seat faster than Teams/Zoom bundling erodes price (low-to-mid single-digit growth likely), while the satellite-ground niche can grow far faster off a small base but carries the highest launch, spectrum, capital, and execution risk [6][18][19]. Much of the value will accrue to companies and private owners that federal statistics never fully capture in this code.

For everything below the summary — full company tables and market values, the complete regulation and demand sections, and detailed underwriting guidance — see the 517810 primer, which this level equals.

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Sources

1. U.S. Census Bureau, 2022 NAICS Manual — definition, scope, exclusions, and 517919→517810 crosswalk; single national industry (517810) under NAICS 51781, 2022. https://www.census.gov/naics/reference_files_tools/2022_NAICS_Manual.pdf
2. U.S. Census Bureau, 2022 Economic Census — receipts, firm count, and concentration ratios (CR4/CR8/CR20/CR50, HHI) for NAICS 517810/51781 (table EC2200SIZECONCEN), 2022. https://data.census.gov/table/ECNSIZE2022.EC2200SIZECONCEN
3. U.S. Census Bureau, County Business Patterns (CBP) 2023 — establishments, employment, and payroll for NAICS 517810, 2023. https://www.census.gov/data/datasets/2023/econ/cbp/2023-cbp.html
4. U.S. Census Bureau, County Business Patterns methodology (coverage/exclusions), 2025. https://www.census.gov/programs-surveys/cbp/technical-documentation/methodology.html
5. IBISWorld, "All Other Telecommunications (NAICS 517919/517810): US market size and growth," 2025. https://www.ibisworld.com/classifications/naics/517919/all-other-telecommunications/
6. Ooma, Inc., Form 10-K (revenue ~$257M; FluentStream and Phone.com acquisitions), 2026. https://www.sec.gov/Archives/edgar/data/1327688/000132768826000009/ooma-20260131.htm
7. 8x8, Inc., "Fourth Quarter and Fiscal Year 2025 Financial Results," 2025–2026. https://www.businesswire.com/news/home/20250516679824/en/
8. Bandwidth Inc., Form 10-K (FY2025) and market data, 2026. https://www.sec.gov/Archives/edgar/data/1514416/000151441626000017/band-20251231.htm
9. Crexendo, Inc. (CXDO) market capitalization, 2026. https://stockanalysis.com/stocks/cxdo/market-cap/
10. IDT Corporation, Form 10-K, Fiscal 2025 (net2phone revenue ~$87.9M), 2025. https://www.sec.gov/Archives/edgar/data/1005731/000149315225016071/form10-k.htm
11. Spok Holdings, Form 10-K, Fiscal 2025 (paging + secure healthcare messaging), 2026. https://www.sec.gov/Archives/edgar/data/1289945/000128994526000010/spok-20251231.htm
12. RingCentral, Form 10-K, Fiscal 2025 (UCaaS/CCaaS), 2026. https://www.sec.gov/Archives/edgar/data/1384905/000138490526000021/rng-20251231.htm
13. Iridium Communications, 2025 Annual Report, 2026. https://www.iridium.com/sites/default/files/2026-04/Iridium_Communications_Inc_2025_Annual_Report.pdf
14. Vonage / Ericsson, "Ericsson completes $6.2 billion Vonage acquisition," 2022. https://njbiz.com/ericsson-completes-6-2b-vonage-acquisition/
15. Intermedia / 26North, "26North Completes Acquisition of AI-Powered Intermedia Intelligent Communications," 2026. https://www.intermedia.com/press-release/26north-completes-acquisition-of-ai-powered-intermedia-intelligent-communications
16. Iridium and Rocket Lab, "Rocket Lab to Acquire Iridium," 2026. https://investor.iridium.com/2026-06-29-Rocket-Lab-to-Acquire-Iridium-in-Historic-Deal%2C-Creating-A-Fully-Vertically-Integrated-Space-Powerhouse-Primed-for-Growth
17. KSAT (Kongsberg Satellite Services), "Ground Network Services" (global antenna footprint; origin of Ground-Station-as-a-Service), 2024. https://www.ksat.no/ground-network-services/
18. MarketsandMarkets, "Satellite Ground Station Market worth $82.72 billion by 2030" (from $40.99B in 2025, 15.1% CAGR), 2025. https://www.marketsandmarkets.com/PressReleases/satellite-ground-station.asp
19. Growth Market Reports, "Ground Station as a Service (GSaaS) Market" (~$0.5B in 2024 to ~$2.5B by 2033, ~19% CAGR), 2024. https://growthmarketreports.com/report/ground-station-as-a-service-market
20. Wiley LLP, "FCC's Looming STIR/SHAKEN Requirements May Raise USF Obligations…" (VoIP E911, USF, Form 499, STIR/SHAKEN, robocall rules), 2025. https://www.wileyconnect.com/fccs-looming-stir-shaken-requirements-may-raise-usf-obligations-and-exposure-for-certain-providers
21. U.S. Federal Communications Commission, "Overview of Earth Station Licensing and License Contents" (Part 25, Form 312, 15-year terms), 2024. https://www.fcc.gov/space/overview-earth-station-licensing-and-license-contents
22. U.S. Departments of State & Commerce, revisions to space-related export controls (ITAR Category XV; EAR 9x515) covering TT&C ground control stations, 2024. https://www.federalregister.gov/documents/2024/10/23/2024-23958/export-administration-regulations-revisions-to-space-related-export-controls
23. National Telecommunications and Information Administration, Memorandum of Understanding Between the FCC and NTIA (federal vs. nonfederal spectrum), 2022. https://www.ntia.gov/other-publication/2022/memorandum-understanding-between-fcc-and-ntia
24. U.S. Department of the Treasury, Committee on Foreign Investment in the United States (CFIUS), 2026. https://home.treasury.gov/policy-issues/international/the-committee-on-foreign-investment-in-the-united-states-cfius