Company lists · Data refreshed September 2026

Top 25 Inside sales outsourcing firms worldwide

Name: Inside sales outsourcing firms worldwide
Creator: RevenueBase
License: https://creativecommons.org/licenses/by/4.0/

Compiled by the RevenueBase Data Team Data refreshed Sep 28, 2026 13,644 companies tracked

RevenueBase identified 13,644 company matches for inside sales outsourcing firms worldwide as of September 2026 and tracks 202,271 professional contacts across them, including 19,580 with verified work emails. The United States is the largest market and London the largest hub.

This list covers company matches for inside sales outsourcing firms worldwide, found by RevenueBase SmartSearch using the meaning of business descriptions in its company graph at Exact. Ranked by professionals tracked, largest first. Rows show recorded descriptions where available, Exact search membership and the snapshot date. Data refreshed September 28, 2026. Country and city lists for inside sales outsourcing firms follow the table.

Published by RevenueBase, a B2B data infrastructure company. This list was built with RevenueBase SmartSearch, 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 RevenueBase SmartSearch · Exact Recorded Sep 28, 2026 How this list was built

13,644Companies

202,271Contacts tracked

19,580Verified emails

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The 25 largest inside sales outsourcing firms worldwide

Ranked by team size

Top 25 of 13,644 company matches for inside sales outsourcing firms worldwide, ordered by professional contacts tracked in RevenueBase, largest first. Recorded Sep 28, 2026. The RevenueBase SmartSearch column shows Exact match membership in this saved search. Click a contact count to view that company's people. Totals use company locations recorded by RevenueBase; the displayed preview is a smaller selection.
#	Company	RevenueBase SmartSearch	Headquarters	Employees	Contacts
1	Emtelco S.A	Exact match	Medellín, ColombiaHQ recorded Sep 28, 2026	10001+	4,998 contacts →
	Exact match “Maximizamos el valor de cada contacto de las empresas con sus clientes, gestionando los procesos de relacionamiento a través de canales tefónicos, virtuales y presenciales.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
2	Liderança Serviços	Exact match	São José, BrazilHQ recorded Sep 28, 2026	10001+	4,504 contacts →
	Exact match “Atuamos nos principais setores de terceirização, e somos pioneiros na implantação de contratos à distância.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
3	Marketsource INC	Exact match	Alpharetta, GA, United StatesHQ recorded Sep 28, 2026	5,001-10,000	3,063 contacts →
	Exact match “MarketSource, an Allegis Group company, is a sales acceleration company focused on delivering better outcomes for many of the world’s most iconic brands.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
4	Advanced Call Center Technologies, LLC	Exact match	Berwyn, PA, United StatesHQ recorded Sep 28, 2026	5,001-10,000	2,774 contacts →
	Exact match “Advanced Call Center Technologies, LLC (ACT) is a premier provider of domestic (USA), near shore and far shore outsourced call center services to the financial services, mortgage…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
5	Stream Global Services	Exact match	Eagan, MN, United StatesHQ recorded Sep 28, 2026	10001+	2,772 contacts →
	Exact match “Stream Global Services is a premium business process outsource (BPO) service provider specializing in customer relationship management solutions including sales, customer care…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
6	Marketstar	Exact match	Ogden, UT, United StatesHQ recorded Sep 28, 2026	1,001-5,000	2,446 contacts →
	Exact match “MarketStar is a global B2B sales outsourcing leader with 38+ years of experience driving predictable revenue growth.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
7	Denave	Exact match	Noida, IndiaHQ recorded Sep 28, 2026	5,001-10,000	2,270 contacts →
	Exact match “We are revenue AI-X-lerators.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
8	Allied Global	Exact match	GuatemalaHQ recorded Sep 28, 2026	5,001-10,000	1,979 contacts →
	Exact match “Regardless of your Company’s size (from Start-ups to Fortune 500), business vertical or service requirements, we act as a seamless extension of your team to help you grow, and…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
9	Webhelp Enterprise	Exact match	Paris, FranceHQ recorded Sep 28, 2026	10001+	1,795 contacts →
	Exact match “The Concentrix B2B sales practice is here to design, build and run projects for our clients.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
10	Full Potential Solutions	Exact match	Waltham, MA, United StatesHQ recorded Sep 28, 2026	1,001-5,000	1,238 contacts →
	Exact match “Full Potential Solutions (FPS) is a new kind of performance-based outsourcing firm that puts culture and employees first, because we believe that happy, fulfilled teams accomplish…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
11	Information Evolution, INC	Exact match	Austin, TX, United StatesHQ recorded Sep 28, 2026	501-1,000	1,238 contacts →
	Exact match “We are a boutique outsourcing firm specializing in keeping our customers' databases up-to-date, accurate, and as robust as possible.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
12	The Office Gurus	Exact match	St Petersburg, FL, RussiaHQ recorded Sep 28, 2026	1,001-5,000	1,198 contacts →
	Exact match “The Office Gurus (TOG) is a global call center and business process outsource provider of customer care, telemarketing, lead generation, appointment setting, order entry, accounts…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
13	crystel.co	Exact match	Amman, JordanHQ recorded Sep 28, 2026	1,001-5,000	1,128 contacts →
	Exact match “Crystel emerged as a leading Outsourcing Service Provider (OSP) since its establishment in Jordan in early 2007.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
14	Cience	Exact match	Miami, FL, United StatesHQ recorded Sep 28, 2026	201-500	1,068 contacts →
	Exact match “CIENCE Technologies, Inc, founded in 2015 and headquartered in Denver, CO, is a pioneering global company in lead generation software and services, committed to transforming the…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
15	B2s Business Support Services	Exact match	Gennevilliers Cedex, FranceHQ recorded Sep 28, 2026	10001+	978 contacts →
	Exact match “Expert de la relation client depuis 1996, b2s est le N°1 de l’externalisation de votre relation client en qualité délivrée.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
16	Transparent BPO	Exact match	Rockville, MD, United StatesHQ recorded Sep 28, 2026	1,001-5,000	972 contacts →
	Exact match “Transparent BPO was founded to provide its clients with superior nearshore contact center services and business process outsourcing at competitive pricing.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
17	Inktel Contact Center Solutions	Exact match	Doral, FL, United StatesHQ recorded Sep 28, 2026	1,001-5,000	902 contacts →
	Exact match “Our Company Inktel is a leading business process outsourcer that specializes in creating personalized call center solutions which enable our clients to increase market share…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
18	Answernet	Exact match	Horsham, PA, United StatesHQ recorded Sep 28, 2026	501-1,000	883 contacts →
	Exact match “If you are interested in growing your business or increasing efficiency, AnswerNet has the expertise, technology, and people to help you take your company to new heights!” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
19	Servestsa	Exact match	Caracas, VenezuelaHQ recorded Sep 28, 2026	n/a	865 contacts →
	Exact match “Statistics first” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
20	Horatio	Exact match	New York, United StatesHQ recorded Sep 28, 2026	1,001-5,000	860 contacts →
	Exact match “Horatio is a premier, tech-enabled outsourcing partner helping ambitious companies scale customer experience and complex business operations without compromising quality…” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
21	Memoryblue	Exact match	Tysons, VA, United StatesHQ recorded Sep 28, 2026	501-1,000	825 contacts →
	Exact match “memoryBlue is the go-to partner for revenue leaders in B2B Tech looking to grow their pipeline engine.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
22	ZAZ Vendas	Exact match	Campinas, BrazilHQ recorded Sep 28, 2026	501-1,000	796 contacts →
	Exact match “Em um mercado cada vez mais competitivo, onde a eficiência em vendas massificadas e externas é um desafio constante, a ZAZ Vendas surge como a resposta definitiva.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
23	CPM International	Exact match	Thame, United KingdomHQ recorded Sep 28, 2026	10001+	777 contacts →
	Exact match “CPM is an international sales outsourcing and customer experience agency.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
24	Sequential Technology International	Exact match	Bethlehem, United StatesHQ recorded Sep 28, 2026	1,001-5,000	758 contacts →
	Exact match “Sequential Tech is the trusted outsource partner of wireline/wireless telecommunication, broadband, cable/MSO, and satellite service providers.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase
25	Abstrakt Marketing Group	Exact match	St Louis, MO, United StatesHQ recorded Sep 28, 2026	501-1,000	724 contacts →
	Exact match “We book the qualified meetings that fill your pipeline for any B2B company ready to grow.” Recorded in the RevenueBase company graph · Sep 28, 2026 · View company records in RevenueBase

RevenueBase SmartSearch

Describe a niche business in your own words. RevenueBase SmartSearch compares the meaning of your description with company business descriptions compiled in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit.

This list uses Exact for “inside sales outsourcing firms”. Each Exact match badge shows membership in that saved search; it is not an individual similarity score or a service-quality rating. Recorded descriptions are shown where available.

Showing 25 of 13,644 inside sales outsourcing firms worldwide

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Inside sales outsourcing firms worldwide at a glance

As of Sep 28, 2026

9.7%Verified-email coverage

14.8Average contacts per company

11-50Median size (employees)

2.1%Largest-city concentration · London

Sep 28, 2026Page data refreshed

Companies by employee count

1-10

6,595

11-50

4,332

51-200

1,842

201-500

533

501-1,000

181

1,001-5,000

5,001-10,000

10001+

Email recency is reported on each country list linked below.

How this list was built

The recorded descriptions help you assess these company matches. Check a company’s website for its current services and locations.

Source: The RevenueBase company graph: 60 million companies and 398.9 million professional contacts resolved from primary sources, queried with RevenueBase SmartSearch, the natural-language company search available to every RevenueBase user.
Coverage: Every country. Country and city lists for inside sales outsourcing firms are linked below.
What qualifies: Company records worldwide whose business descriptions match “inside sales outsourcing firms” by meaning at the Exact setting. Descriptions are compiled in the RevenueBase company graph from public websites, profiles and company information where available; they are not guaranteed quotations from the company's website.
RevenueBase SmartSearch: Describe a niche company in your own words to find businesses by meaning. Exact, Similar, Related and Broad control the breadth of RevenueBase SmartSearch. This saved list uses Exact. Each row's Exact match badge shows inclusion in that search, not an individual score or a service-quality judgment.
Public preview: The public preview omits records without a verified work email. Dataset totals and geographic summaries describe the full matched records before these preview filters.
Match quality: RevenueBase's August 25, 2026 study assessed 4,198 description/company pairs across matching settings. The publisher reports 86% good or better at Exact. This evaluates the method across queries; it does not audit this individual list. Recorded company descriptions, where available, help you judge each match yourself. Read the full methodology: how the lists are built and what the study measures.
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 displayed company carries at least one verified work email. RevenueBase tracks 19,580 professional contacts with verified work emails across the full matched dataset. 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 28, 2026. Lists refresh periodically as the graph is re-checked.
Record context: Company records and descriptions can change. Check the company's website for its current services and locations.

Inside sales outsourcing firms by location

70 lists · largest first

Every Inside sales outsourcing firms 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 SmartSearch?

RevenueBase SmartSearch finds niche companies by the meaning of their business descriptions in the RevenueBase company graph. Exact, Similar, Related and Broad control how closely companies must fit your description. This list uses Exact for “inside sales outsourcing firms”; each Exact match badge shows search membership, not an individual similarity or quality score.

How many inside sales outsourcing firms are there worldwide?

RevenueBase identified 13,644 company matches for inside sales outsourcing firms worldwide as of September 2026, using the meaning of business descriptions at Exact. This is the recorded matched set in the RevenueBase company graph.

What is the largest company on this list?

Emtelco S.A tops the displayed preview by professional contacts tracked in RevenueBase. Recorded headquarters appear in the company rows.

Which country has the most inside sales outsourcing firms?

The United States leads with 2,898 companies, followed by India (1,194) and the United Kingdom (868). Every inside sales outsourcing firms list by country and city is linked on this page.

Which city has the most inside sales outsourcing firms?

London leads with 284 company records, followed by Pune (218) and New York (145).

How do I get contact information for these companies?

A free RevenueBase account lets you run this exact search and work limited free results with 500 credits to start. Upgrading provides access to the 19,580 professional contacts with verified work emails tracked across these 13,644 companies; direct dials are available where recorded.

How current is this list?

The list refreshes periodically as the company graph is re-checked. This page's figures were pulled on September 28, 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 SmartSearch, 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.