Company lists · Data refreshed September 2026

Top 25 Sales development call centers based in the United Kingdom

RevenueBase identified 665 sales development call centers headquartered in the United Kingdom as of September 2026 and tracks 6,242 professional contacts across them, including 1,326 with verified work emails. London is the largest hub.

This list covers sales development call centers headquartered in the United Kingdom, 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 29, 2026.

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 29, 2026 86% judged on-target in blind review
665Companies
6,242Contacts tracked
1,326Verified emails
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The 25 largest sales development call centers based in the United Kingdom

Ranked by team size
Top 25 of 665 sales development call centers based in the United Kingdom, ranked by team size, largest first. Data refreshed Sep 29, 2026. RevenueBase Smart Search rates how each company's information relates to sales development call centers: 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
1Partial evidenceBrighton, United KingdomHQ checked Sep 29, 2026201-500243 contacts →

Partial evidence

“The Telemarketing Company is one of the UK's most trusted telemarketing agencies, delivering flexible, high-quality voice services, including pre and post sales research…”

Source: RevenueBase Database · checked Sep 29, 2026
2Strong evidenceLondon, United KingdomHQ checked Sep 29, 202651-200205 contacts →

Strong evidence

“EngageTech is the leading sales development partner for complex B2B technology companies operating in multi-stakeholder, enterprise sales environments.”

Source: RevenueBase Database · checked Sep 29, 2026
3Indirect evidenceLiverpool, United KingdomHQ checked Sep 29, 202651-200164 contacts →

Indirect evidence

“Inside is a global agency dedicated to delivering growth and revenue opportunities for B2B tech companies.”

Source: RevenueBase Database · checked Sep 29, 2026
4Indirect evidenceBirmingham, United KingdomHQ checked Sep 29, 202651-200119 contacts →

Indirect evidence

“GCL, with its unique, non-scripted approach to telemarketing and related marketing services, has for over 30 years established an enviable reputation for providing winning lead…”

Source: RevenueBase Database · checked Sep 29, 2026
5Partial evidenceExeter, United KingdomHQ checked Sep 29, 202651-200116 contacts →

Partial evidence

“Since 2016, Air Marketing has been the trusted outsourced sales and lead generation agency in the UK for ambitious B2B businesses.”

Source: RevenueBase Database · checked Sep 29, 2026
6Indirect evidenceNewcastle Upon Tyne, United KingdomHQ checked Sep 29, 202651-200115 contacts →

Indirect evidence

“More than SDR Outsourcing.”

Source: RevenueBase Database · checked Sep 29, 2026
7Indirect evidenceDoxford International Business Park, United KingdomHQ checked Sep 29, 20261,001-5,000114 contacts →

Indirect evidence

“EC Outsourcing is one of the UK's leading outsourced contact centres.”

Source: RevenueBase Database · checked Sep 29, 2026
8Partial evidenceManchester, United KingdomHQ checked Sep 29, 202611-50104 contacts →

Partial evidence

“Flowd is an award-winning sales prospecting specialist based in the UK, Europe & US.”

Source: RevenueBase Database · checked Sep 29, 2026
9Partial evidenceTunbridge Wells, United KingdomHQ checked Sep 29, 202651-20082 contacts →

Partial evidence

“Alliance Sales Support Services provides effective and sustainable sales solutions for your business.”

Source: RevenueBase Database · checked Sep 29, 2026
10Partial evidenceSheffield, United KingdomHQ checked Sep 29, 2026201-50075 contacts →

Partial evidence

“Voice is an agency that specialises in customer acquisition, development and retention programs.”

Source: RevenueBase Database · checked Sep 29, 2026
11Strong evidenceHitchin, United KingdomHQ checked Sep 29, 202651-20065 contacts →

Strong evidence

“Excelerate360 offers business development and sales outsourcing services for B2B software and technology companies in the UK, Europe, and North America.”

Source: RevenueBase Database · checked Sep 29, 2026
12Partial evidenceCovent Garden, United KingdomHQ checked Sep 29, 202611-5061 contacts →

Partial evidence

“Angsana is the UK’s most respected new business development and lead generation agency for Healthcare & Life Sciences, Marketing Services and Technology companies.”

Source: RevenueBase Database · checked Sep 29, 2026
13Partial evidenceLondon, United KingdomHQ checked Sep 29, 202651-20059 contacts →

Partial evidence

“Looking to fill your calendar with qualified calls?”

Source: RevenueBase Database · checked Sep 29, 2026
14Strong evidenceRomsey, United KingdomHQ checked Sep 29, 2026201-50054 contacts →

Strong evidence

“We are an established AI-enabled call centre specialising in every aspect of sales and customer service.”

Source: RevenueBase Database · checked Sep 29, 2026
15Partial evidenceLondon, United KingdomHQ checked Sep 29, 202651-20048 contacts →

Partial evidence

“At Fly Pie, sales outsourcing isn’t a “done-for-you” service, it’s a growth engine we build with you.”

Source: RevenueBase Database · checked Sep 29, 2026
16Indirect evidencePortsmouth, United KingdomHQ checked Sep 29, 202611-5047 contacts →

Indirect evidence

“4Marketing is a direct marketing agency devoted to generating new business opportunities for its clients through its focused new generation of telemarketing professionals.”

Source: RevenueBase Database · checked Sep 29, 2026
17Indirect evidenceEllesmere Port, United KingdomHQ checked Sep 29, 202651-20045 contacts →

Indirect evidence

“Advance Connects are a B2B telemarketing, lead generation & appointment scheduling experts, operating within various sectors including construction, built environment, industrial…”

Source: RevenueBase Database · checked Sep 29, 2026
18Partial evidenceTavistock, United KingdomHQ checked Sep 29, 202611-5044 contacts →

Partial evidence

“With over three decades of experience, we partner with B2B sales and marketing teams to drive and nurture new customer acquisition - securing conversations with the right…”

Source: RevenueBase Database · checked Sep 29, 2026
19Indirect evidenceSouthend On Sea, United KingdomHQ checked Sep 29, 202611-5043 contacts →

Indirect evidence

“Beanstalk is an integrated B2B Telemarketing and Lead Generation agency dedicated to helping our customers win new business.”

Source: RevenueBase Database · checked Sep 29, 2026
20Indirect evidenceLeeds, United KingdomHQ checked Sep 29, 202651-20043 contacts →

Indirect evidence

“B2B and B2C outsourced Telemarketing agency.”

Source: RevenueBase Database · checked Sep 29, 2026
21Partial evidenceBristol, United KingdomHQ checked Sep 29, 202611-5038 contacts →

Partial evidence

“Highly qualified B2B Sales Appointments you can trust.”

Source: RevenueBase Database · checked Sep 29, 2026
22Indirect evidenceHebden Bridge, United KingdomHQ checked Sep 29, 202611-5038 contacts →

Indirect evidence

“We are the people who make meetings happen.”

Source: RevenueBase Database · checked Sep 29, 2026
23Indirect evidenceGlasgow, United KingdomHQ checked Sep 29, 202611-5037 contacts →

Indirect evidence

“Founded in 2002, eContact Services is a telemarketing agency specializing in lead generation and appointment setting for communication service providers-fixed and mobile…”

Source: RevenueBase Database · checked Sep 29, 2026
24Partial evidenceEwell, United KingdomHQ checked Sep 29, 202651-20035 contacts →

Partial evidence

“1 Stop Data offers the best of breed Marketing, Lead Generation and Call Centre services.”

Source: RevenueBase Database · checked Sep 29, 2026
25Indirect evidencePortsmouth, United KingdomHQ checked Sep 29, 202651-20033 contacts →

Indirect evidence

“Working with clients across a variety of sectors, Paragon is a leading provider of B2B lead generation and appointment setting marketing projects with vast experience in creating…”

Source: RevenueBase Database · checked Sep 29, 2026

Showing 25 of 665 sales development call centers based in the United Kingdom

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Sales development call centers based in the United Kingdom at a glance

As of Sep 29, 2026
21.2%Verified-email coverage
9.4Average contacts per company
1-10Median size (employees)
29.5%Largest-city concentration · London
Sep 29, 2026Page data refreshed

Companies by employee count

1-10
403
11-50
196
51-200
46
201-500
14
501-1,000
2
1,001-5,000
1
10001+
1

Email recency for this list is measured worldwide rather than for United Kingdom, so it is reported there. Company counts and contact totals on this page are exact for United Kingdom, over 665 companies.

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 sales development call centers, 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.
What qualifies
Companies headquartered in the United Kingdom whose own description of what they do matches “sales development call centers”. 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 sales development call centers), 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 sales development call centers, and records with no verified work email. Companies headquartered outside United Kingdom are excluded even when they keep an office there.
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, 1,326 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 29, 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.

Sales development call centers by metro

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 sales development call centers, 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 sales development call centers are there based in the United Kingdom?

RevenueBase identified 665 sales development call centers headquartered in the United Kingdom 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?

The Telemarketing Company, headquartered in Brighton, tops this list with the largest team on record.

Which city has the most sales development call centers?

London leads with 196 headquartered companies, followed by Manchester (32) and Birmingham (17).

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 1,326 verified decision-maker contacts tracked across these 665 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 29, 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.