Company lists · Data refreshed September 2026

Top 25 Calling companies worldwide

RevenueBase identified 7,651 calling companies worldwide as of September 2026 and tracks 146,623 professional contacts across them, including 28,839 with verified work emails. The United States is the largest market and London the largest hub.

This list covers calling companies worldwide, matched on what each company actually does as described in its own words. Ranked by team size, largest first. Every row shows the company's own description, its RevenueBase Smart Search rating, and when it was last checked. Data refreshed September 21, 2026. Country and city lists for calling companies follow the table.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase Smart Search, the natural-language company search RevenueBase customers use to build their own targeted lists and unlock verified emails and direct dials at the companies on them. How these lists are built and judged.

How to read this list HQ checked on every row RevenueBase Smart Search rating on every row Refreshed Sep 21, 2026 86% judged on-target in blind review
7,651Companies
146,623Contacts tracked
28,839Verified emails
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The 25 largest calling companies worldwide

Ranked by team size
Top 25 of 7,651 calling companies worldwide, ranked by team size, largest first. Data refreshed Sep 21, 2026. RevenueBase Smart Search rates how each company's information relates to calling companies: strong evidence (its own description names it), partial (names part of it), indirect (matched on the rest of its profile rather than the description shown). Click a contact count to view that company's people.
#CompanyRevenueBase Smart SearchHeadquartersEmployeesContacts
1Indirect evidenceIstanbul, TürkiyeHQ checked Sep 21, 20265,001-10,00012,790 contacts →

Indirect evidence

“Turkcell is a converged telecommunication and technology services provider, founded and headquartered in Türkiye.”

Source: RevenueBase Database · checked Sep 21, 2026
2Indirect evidenceLittle Rock, AR, United StatesHQ checked Sep 21, 202610001+7,275 contacts →

Indirect evidence

“Windstream and Uniti have merged - Please follow us at Uniti Group, Inc.”

Source: RevenueBase Database · checked Sep 21, 2026
3Indirect evidenceLondon, United KingdomHQ checked Sep 21, 202610001+6,767 contacts →

Indirect evidence

“Vodafone Business is part of the Vodafone Group.”

Source: RevenueBase Database · checked Sep 21, 2026
4Indirect evidencePhoenix, AZ, United StatesHQ checked Sep 21, 20261,001-5,0006,379 contacts →

Indirect evidence

“Cable One Business offers scalable, reliable, and efficient solutions so that the businesses we serve can be successful.”

Source: RevenueBase Database · checked Sep 21, 2026
5Indirect evidenceStamford, CT, United StatesHQ checked Sep 21, 202610001+3,044 contacts →

Indirect evidence

“Our story starts with understanding that connectivity powers everything you do, and we make it stronger.”

Source: RevenueBase Database · checked Sep 21, 2026
6Indirect evidenceGurgaon, IndiaHQ checked Sep 21, 202610001+2,760 contacts →

Indirect evidence

“The B2B arm of Bharti Airtel, we are India's leading provider of secure and reliable connectivity, technology, and communications solutions.”

Source: RevenueBase Database · checked Sep 21, 2026
7Indirect evidenceQuincy, MA, United StatesHQ checked Sep 21, 20261,001-5,0002,270 contacts →

Indirect evidence

“Granite is a dynamic and rapidly growing company serving the exciting and demanding Telecommunications market.”

Source: RevenueBase Database · checked Sep 21, 2026
8Indirect evidenceTimbó, BrazilHQ checked Sep 21, 20261,001-5,0001,807 contacts →

Indirect evidence

“Somos uma empresa de telecomunicações com 28 anos de atuação.”

Source: RevenueBase Database · checked Sep 21, 2026
9Indirect evidenceOsasco, BrazilHQ checked Sep 21, 20261,001-5,0001,733 contacts →

Indirect evidence

“Com mais de funcionários, a Ability Tecnologia e Serviços S.A.”

Source: RevenueBase Database · checked Sep 21, 2026
10Indirect evidenceLondon, United KingdomHQ checked Sep 21, 20261,001-5,0001,568 contacts →

Indirect evidence

“Gamma Communications is a leading provider of technology-based communication solutions across Europe.”

Source: RevenueBase Database · checked Sep 21, 2026
11Indirect evidenceDar Es Salaam, TanzaniaHQ checked Sep 21, 20261,001-5,0001,220 contacts →

Indirect evidence

“TTCL Corporation is a Tanzania's leading integrated communications Corporation, with a comprehensive portfolio of products and services including local, national and international…”

Source: RevenueBase Database · checked Sep 21, 2026
12Indirect evidenceVancouver, WA, United StatesHQ checked Sep 21, 2026501-1,0001,133 contacts →

Indirect evidence

“Integra is Allstream.”

Source: RevenueBase Database · checked Sep 21, 2026
13Indirect evidenceLondrina, BrazilHQ checked Sep 21, 2026501-1,0001,001 contacts →

Indirect evidence

“A Sercomtel é a empresa paranaense de telecomunicações que oferece soluções completas em telefonia.”

Source: RevenueBase Database · checked Sep 21, 2026
14Indirect evidenceKarachi, PakistanHQ checked Sep 21, 20261,001-5,000890 contacts →

Indirect evidence

“Multinet Pakistan is one of the premier information and communication solution providers for leading enterprises in the region.”

Source: RevenueBase Database · checked Sep 21, 2026
15Indirect evidenceSão Paulo, BrazilHQ checked Sep 21, 2026501-1,000819 contacts →

Indirect evidence

“Com mais de 25 anos de experiência, a Mundivox é uma operadora licenciada pela Anatel, especializada em soluções integradas de comunicação para o mercado corporativo.”

Source: RevenueBase Database · checked Sep 21, 2026
16Indirect evidenceTehran, IranHQ checked Sep 21, 2026501-1,000777 contacts →

Indirect evidence

“Data Transmission company of Asiatech (#asiatech) was established in 2003 to provide IT-based services and obtained PAP license from the Communications Regulatory Authority (CRA)…”

Source: RevenueBase Database · checked Sep 21, 2026
17Indirect evidenceKanata, CanadaHQ checked Sep 21, 20261,001-5,000691 contacts →

Indirect evidence

“ShoreTel is now part of Mitel.”

Source: RevenueBase Database · checked Sep 21, 2026
18Indirect evidenceFareham, United KingdomHQ checked Sep 21, 2026501-1,000655 contacts →

Indirect evidence

“Onecom is the UK’s leading business telecoms and cloud communications provider managing over a million services for business customers - delivering communication services and…”

Source: RevenueBase Database · checked Sep 21, 2026
19Indirect evidenceSunnyvale, CA, United StatesHQ checked Sep 21, 2026501-1,000606 contacts →

Indirect evidence

“Ooma delivers phone, messaging, video and advanced communications services that are easy to implement and provide great value.”

Source: RevenueBase Database · checked Sep 21, 2026
20Indirect evidenceLos Angeles, CA, United StatesHQ checked Sep 21, 20261,001-5,000542 contacts →

Indirect evidence

“TelePacific company is now TPx Communications.”

Source: RevenueBase Database · checked Sep 21, 2026
21Indirect evidenceHyderabad, IndiaHQ checked Sep 21, 2026201-500527 contacts →

Indirect evidence

“Telecom Applications are one of the fastest-changing technologies of today.”

Source: RevenueBase Database · checked Sep 21, 2026
22Indirect evidenceSão Paulo, BrazilHQ checked Sep 21, 202651-200518 contacts →

Indirect evidence

“A DDS é uma empresa de tecnologia especializada na integração de sistemas.”

Source: RevenueBase Database · checked Sep 21, 2026
23Indirect evidenceMiguel Hidalgo, MexicoHQ checked Sep 21, 2026501-1,000507 contacts →

Indirect evidence

“Somos C3NTRO, una empresa mexicana de clase mundial con 15 años de experiencia en Telecomunicaciones.”

Source: RevenueBase Database · checked Sep 21, 2026
24Indirect evidenceMarkham, ON, CanadaHQ checked Sep 21, 2026201-500454 contacts →

Indirect evidence

“Sangoma Technologies Corporation (TSX: STC; Nasdaq: SANG) is a global leader in essential business communications.”

Source: RevenueBase Database · checked Sep 21, 2026
25Indirect evidenceConcord, MA, United StatesHQ checked Sep 21, 202651-200435 contacts →

Indirect evidence

“NHC is THE communications STACK provider™.”

Source: RevenueBase Database · checked Sep 21, 2026

Showing 25 of 7,651 calling companies worldwide

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Calling companies worldwide at a glance

As of Sep 21, 2026
19.7%Verified-email coverage
19.2Average contacts per company
11-50Median size (employees)
1.6%Largest-city concentration · London
Sep 21, 2026Page data refreshed

Companies by employee count

1-10
3,546
11-50
3,023
51-200
752
201-500
169
501-1,000
61
1,001-5,000
48
5,001-10,000
11
10001+
17

Email recency is reported on each country list linked below.

How this list was built

Company categories are rarely black and white. RevenueBase reads each company's own description of its business to decide whether it belongs among calling companies, so some rows will be adjacent to the category rather than pure plays. The description and RevenueBase Smart Search rating on every row are there so you can check each match yourself.

Source
The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase Smart Search, the natural-language company search available to every RevenueBase user.
Coverage
Every country. Country and city lists for calling companies are linked below.
What qualifies
Companies worldwide whose own description of what they do matches “calling companies”. Matching reads each company's description, not its industry code or its name.
RevenueBase Smart Search
RevenueBase Smart Search is how this list is assembled and how each row is rated. RevenueBase's data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to a category defined in a user's own words. Each row is rated strong evidence (its own description names calling companies), partial evidence (it names part of the category) or indirect evidence (the description shown names none of it and the match rests on the rest of the company's profile). The description supporting each rating is quoted on the row.
What we exclude
Companies whose own description does not clearly place them among calling companies, and records with no verified work email.
Match quality
In blind human judging of this matching method, 86% of matched companies were on target. Expect roughly 1 in 7 rows to be adjacent to the category rather than a pure play. Every row shows the company's own description and its RevenueBase Smart Search rating so you can judge each match yourself. Read the full methodology: how the lists are built, how the judging worked, and what the figure means.
Ranking
Team size, largest first: companies are ordered by the number of professionals RevenueBase tracks at each one. Employee ranges shown are reported bands, for context.
Verification
Every listed company carries at least one verified work email, 28,839 across the full list. Contacts re-verify on a rolling cadence, and each contact's own verification date is shown inside RevenueBase.
Refresh
This page's figures were pulled from the company graph on September 21, 2026. Lists refresh periodically as the graph is re-checked.
Corrections
Wrong category, wrong headquarters, or a company that has closed? Use “Report an issue” on any row. Reports go to the RevenueBase Data Team and feed back into the company graph.

Calling companies by location

30 lists · largest first

Every Calling companies list RevenueBase publishes, by country and city. Counts are matching companies in each list as of its own refresh date.

Countries

Cities

Frequently asked

What is RevenueBase Smart Search?

RevenueBase Smart Search is how RevenueBase decides which companies belong on this list and how strongly each one fits. Its data engine and AI assess a company's LinkedIn profile, information supplied directly by the company, its website and other publicly available information, then relate it to the category the list is about. Each row is rated strong evidence when the company's own description names calling companies, partial evidence when it names part of the category, and indirect evidence when the description shown names none of it and the match rests on the rest of the company's profile.

How many calling companies are there worldwide?

RevenueBase identified 7,651 calling companies worldwide as of September 2026, matched on each company's own description of what it does rather than its industry code.

What is the largest company on this list?

Turkcell, headquartered in Maltepe, tops this list with the largest team on record.

Which country has the most calling companies?

The United States leads with 1,952 companies, followed by the United Kingdom (870) and Brazil (525). Every calling companies list by country and city is linked on this page.

Which city has the most calling companies?

London leads with 122 headquartered companies, followed by Sao Paulo (119) and New York (59).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work the top results, verified emails and direct dials included. Upgrading unlocks all 28,839 verified decision-maker contacts tracked across these 7,651 companies.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 21, 2026.

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About this data

RevenueBase is a B2B data infrastructure company. Its company graph covers 60 million companies and 398.9 million professional contacts, with emails verified on a rolling cadence rather than scraped once and left to decay. These company lists are generated directly from that graph with RevenueBase Smart Search, the same natural-language company search every RevenueBase user has: describe a market in plain words, get the companies that match, and add verified emails and direct dials for the people at them. It is the same data that powers RevenueBase's B2B data products, and a free account includes 500 credits to start. How these lists are built and judged.