These companies operate in the telecommunications sector within the United Kingdom. The list comprises primarily large, established firms. Vodafone uses technology to connect people globally, BT Group is a global communications services company, and Openreach is the UK's digital network business. EE is a mobile communications company, Virgin Media O2 provides broadband and mobile networks, and Vodafone Business offers various services to businesses.
A clear pattern is the concentration of headquarters in London, with most of the largest companies, such as Vodafone, BT Group, and EE, based there. Reading also appears as a significant hub for telecommunications firms, housing companies like Virgin Media, Three UK, and O2 (Telef贸nica UK).
| # | Company | Employees | |||
|---|---|---|---|---|---|
| 1 |
Vodafonevodafone.com
Using technology to connect people globally, drive social change, and improve lives while emphasizing the importance of humanity and collaboration |
142,740 | |||
| 2 | 73,712 | ||||
| 3 |
Openreachopenreach.com
This company is the UK's digital network business, connecting homes, businesses, and more to the world with a focus on high-quality service |
16,885 | |||
| 4 | 12,146 | ||||
| 5 |
Virgin Media O2virginmediao2.co.uk
Provides fastest broadband and largest mobile network in the UK, focusing on customer-first connectivity services and network upgrades. |
8,272 | |||
| 6 |
Vodafone Businessvodafone.com
Providing mobile, fixed, unified communications, IoT, cloud, and security services to businesses globally, regionally, and locally. |
8,100 | |||
| 7 |
Virgin Mediajobs.virginmediao2.co.uk
Providing ultrafast broadband and fibre optic network services to connect millions of homes and businesses with reliable internet access. |
7,691 | |||
| 8 |
Three UKthreev1-1481200-gb-engb.sr-attrax.com
Provides mobile network services, including 3G, 4G, and 5G, covering 99% of the UK outdoor population and sponsoring Chelsea FC. |
6,239 | |||
| 9 |
O2 (Telef贸nica UK)o2.co.uk
Leading UK mobile network operator providing 2G to 5G services, retail stores, WiFi, and partnerships with Tesco Mobile and entertainment venues. |
5,371 | |||
| 10 |
Colt Technology Servicescolt.net
Global digital infrastructure provider connecting businesses across 40+ countries with extensive networks, customer-focused innovation, and reliable connectivity solutions. |
5,107 | |||
| 11 |
IHS Towersihstowers.com
A leading tower infrastructure company with over 40,000 towers in emerging markets, specializing in hybrid energy solutions and network monitoring |
3,497 | |||
| 12 |
Liberty Globallibertyglobal.com
Global provider of broadband, mobile communications, and infrastructure investing in fibre, 5G networks, content, technology, and innovation. |
2,833 | |||
| 13 |
Telent Technology Services Ltdtelent.com
Leading technology company specializing in designing, building, operating, and maintaining critical digital infrastructure for public sector, transport, emergency services, and network providers |
2,675 | |||
| 14 |
Gammagammagroup.co
Gamma is a leading supplier of Unified Communications services in the UK, Germany, Spain, and Benelux, offering robust solutions for communication and collaboration |
2,588 | |||
| 15 |
Telecom Jobstelecomjobs.uk
The company aims to be the top resource for telecom jobs in the UK by connecting jobseekers and employers in the industry |
2,468 | |||
| 16 |
Senture, LLCsenture.com
A premier domestic contact center solutions company providing comprehensive service support nationally, focused on delivering excellent customer experiences and award-winning support services |
2,129 | |||
| 17 |
TalkTalktalktalkgroup.com
A dynamic company welcoming innovative thinkers and problem-solvers who challenge the status quo, offering a fun, flexible, and rewarding work environment |
2,100 | |||
| 18 |
CityFibrecityfibre.com
We build open-access fiber networks across the UK, providing fast and reliable broadband, Ethernet, and mobile connections to homes, businesses, and institutions |
1,800 | |||
| 19 |
Ofcomofcom.org.uk
Regulating UK communications, ensuring fair home phone and mobile services, overseeing TV, radio, and content, protecting consumers, promoting access to technology |
1,700 | |||
| 20 |
Arqivaarqiva.com
The company is a leading provider of national terrestrial television and radio broadcasting services in the UK, alongside international channel distribution and data management for connected devices |
1,620 | |||
| 21 |
Kelly Groupkelly.co.uk
Providing end-to-end telecommunications network services including planning, design, installation, commissioning, and maintenance across multiple industries nationwide. |
1,561 | |||
| 22 | 1,407 | ||||
| 23 |
Lyca Mobile UKlycamobile.co.uk
A global mobile virtual network operator offering low-cost international calls, data, and minutes to 23 countries with a digital-first approach |
1,369 | |||
| 24 |
Hyperoptichyperoptic.com
The company provides ultra-reliable full-fibre broadband with top speeds, no mid-contract price hikes, and exceptional customer service |
1,358 | |||
| 25 |
Boldyn Networksmobilitie.com
A US-based telecommunications infrastructure company providing wireless solutions for robust coverage and 5G services at large venues and cities |
1,286 | |||
Want more companies than this list?This page shows the largest ones only. Connect to Tamtam to see every company that matches, filter by size, industry or growth, and reach their decision-makers. | |||||
| 26 |
YouFibreyoufibre.com
A provider of gigafast broadband speeds with a focus on flawless customer support, fair contracts, and affordable pricing since 2019 |
1,223 | |||
| 27 |
Telekom Networks Malawi PLCtnm.co.mw
A pioneering mobile network in Malawi offering advanced broadband services including voice, data connectivity, video calls, music streaming, and high-speed internet access |
1,043 | |||
| 28 |
Maintelmaintel.co.uk
Provider of cloud communications and managed services, specializing in digital transformation for public and private sectors Delivering digital workplace, customer experience, and secure connectivity solutions globally |
946 | |||
| 29 |
Inmarsatviasat.com
Account closed, follow Viasat company page for satellite communications news due to acquisition. No longer posting here. |
939 | |||
| 30 |
Helios Towersheliostowers.com
Builds, owns, operates telecom passive infrastructure across Africa, enabling mobile operators to expand coverage and improve network access efficiently. |
933 | |||
| 31 |
Wireless Logicwirelesslogic.com
Provides global IoT connectivity solutions with secure, flexible management across multiple networks for diverse industries and applications worldwide. |
874 | |||
| 32 |
EXA Infrastructureexainfra.net
A leading digital infrastructure platform in Europe and North America, owning a vast fibre network, data centers, and sub-sea routes for optimal connectivity |
846 | |||
| 33 |
Africell Groupafricell.com
A mobile technology company providing fast, low-cost, and reliable mobile network coverage and innovative services to over sixteen million subscribers in sub-Saharan Africa |
845 | |||
| 34 |
Arrow Business Communicationsaro.tech
Provides cloud, collaboration, and sustainability IT solutions to major UK clients including FTSE100 companies, law firms, universities, NHS, and emergency services. |
836 | |||
| 35 |
GCXgcxworld.com
Network services enabling digital transformation through managed SD-WAN, hybrid networks, and extensive subsea cloud connectivity across emerging markets and Asia. |
810 | |||
| 36 |
Industriaindustria.com
A leading provider of broadband network and entertainment solutions, offering turn-key services to operators and achieving significant milestones in connectivity and innovation |
788 | |||
| 37 | 751 | ||||
| 38 |
Onecomonecom.co.uk
The UK's top business telecoms provider offering communication services and unified solutions like fixed-line voice, connectivity, and managed cloud to 80,000+ clients |
742 | |||
| 39 | 698 | ||||
| 40 |
Indigoindigotg.com
Indigo engineers digital infrastructure for network owners worldwide, focusing on sustainability, safety, and connectivity for businesses and communities |
663 | |||
| 41 |
Kelly Communications Ltd.kelly.co.uk
A versatile mobile engineering workforce provider for telecommunications networks, broadband, and satellite services in the UK, offering installation, maintenance, and project management solutions |
649 | |||
| 42 |
Lycatellycagroup.com
The company is a global market leader in the calling card market and Europe's largest International MVNO Mobile brand, serving millions of customers worldwide |
647 | |||
| 43 |
WHP Telecoms Limitedwhptelecoms.com
A leading UK supplier of network infrastructure services, offering deployment, support, and management of communications networks with over 35 years of experience |
636 | |||
| 44 |
Global Marineglobalmarine.co.uk
A market leader in subsea cable installation and maintenance solutions for telecoms and oil & gas sectors with specialized vessels and capabilities |
630 | |||
| 45 |
Virgin Media Businessvirginmediabusiness.co.uk
Delivers innovative networking and communication products, applications, and services to help UK organizations overcome challenges and achieve digital transformation through ultrafast connections. |
624 | |||
| 46 | 604 | ||||
| 47 |
Gigacleargigaclear.com
Specialist fibre-to-the-premises provider expanding high-speed internet access in rural communities through state-of-the-art networks, government programs, and commercial investments |
594 | |||
| 48 |
DRCdrcltd.co.uk
With over 30 years of experience, we provide bespoke telecom solutions for UK businesses, focusing on reliability, scalability, and exceptional service Contact us today |
569 | |||
| 49 |
Zen Internetzen.co.uk
Telecommunications and technology service provider offering business broadband, Ethernet, data services, and expert cloud solutions for diverse business needs. |
562 | |||
| 50 |
MYCOM OSImycom-osi.com
Provide network assurance and service experience solutions for CSPs and enterprises to manage 5G and enterprise services efficiently. |
557 | |||
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How this list is built
Every company on this list has a Tamtam company profile. The industry is the one the company gives on LinkedIn; categories such as SaaS or fintech are classified by Tamtam's AI from the company's website and LinkedIn page; and the headquarters city must match the company's own address. Companies are ranked by the number of employees on LinkedIn, and the list is refreshed every night. Classifications can be wrong, so treat the list as a starting point rather than an official ranking. Last updated Nov 12, 2026.
More company lists in the United Kingdom
- The largest companies in the United Kingdom 36,548
- Multinational companies in the United Kingdom 7,458
- Financial services firms in the United Kingdom 3,711
- Financial Services companies in the United Kingdom 3,696
- Retail chains in the United Kingdom 3,289
- Professional services firms in the United Kingdom 2,706
- Software Development companies in the United Kingdom 2,600
- Manufacturers in the United Kingdom 2,159
- Companies with in-house R&D in the United Kingdom 1,930
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- Consulting firms in the United Kingdom 1,298
- E-commerce companies in the United Kingdom 1,246
- Hardware manufacturers in the United Kingdom 1,239
- Family-owned companies in the United Kingdom 1,224
- Hospitality companies in the United Kingdom 1,204
- Critical infrastructure operators in the United Kingdom 1,195
- Wellness and Fitness Services companies in the United Kingdom 1,151
- Retail Apparel and Fashion companies in the United Kingdom 1,085
- Subscription businesses in the United Kingdom 1,077
- Distributors and wholesalers in the United Kingdom 1,060