BT Group plc is a British multinational telecommunications holding company headquartered in London, England. It has operations in around 180 countries and is the largest provider of fixed-line, broadband and mobile services in the UK, and also provides subscription television and IT services.
Communications in Gibraltar comprise a wide range of telephony systems, Internet access, broadcasting and satellite control. There is also printed and online media. Regulation of telecommunications and broadcasting are the responsibility of the Gibraltar Regulatory Authority (GRA), established by means of the Gibraltar Regulatory Authority Act in 2000.
The Isle of Man has an extensive communications infrastructure consisting of telephone cables, submarine cables, and an array of television and mobile phone transmitters and towers.
Telefónica, S.A. is a Spanish multinational telecommunications company with registered office and headquarters located in two different places, both in Madrid, Spain. It is one of the largest telephone operators and mobile network providers in the world. It provides fixed and mobile telephony, broadband, and subscription television, operating in Europe and the Americas.
Telecommunications in the United Kingdom have evolved from the early days of the telegraph to modern broadband and mobile phone networks with Internet services.
China United Network Communications Group is a Chinese state-owned telecommunications operator. Started as a wireless paging and GSM mobile operator, it currently provides a range of services including mobile network, long-distance, local calling, data communication, Internet services, and IP telephony. China Unicom is the third-largest wireless carrier in China and the sixth largest mobile provider in the world as of 2022.
O2 (typeset as O2) is a global brand name owned by the Spanish telecommunications company Telefónica. The company uses the O2 brand for its subsidiaries in the United Kingdom and Germany. Since 2018, it is also used as an online-only flanker brand in Spain.
Telefónica Ireland was a broadband and telecommunications provider in Ireland that traded under the O2 brand (typeset as O2). O2 Ireland was previously called Esat Digifone when it was owned by Esat Telecommunications (and Telenor) from 1997 to 2006.
BT Communications (Ireland) Limited is a telecommunications and internet company in Ireland. It is a subsidiary of BT Group plc.
Mercury Communications was a national telephone company in the United Kingdom, formed in 1981 as a subsidiary of Cable & Wireless, to challenge the then-monopoly of British Telecom (BT). Although it proved only moderately successful at challenging BT's dominance, it led the way for new communication companies to attempt the same.
The FreeMove alliance is a business alliance of mobile telecommunications companies based in Europe.
O2 Czech Republic (operating under the O2 brand) is a major integrated operator in the Czech Republic. It is now operating more than six million lines, both fixed and mobile, making it one of the Czech Republic's largest providers of fully converged services. O2 Czech Republic operates a fixed and mobile network including a 3rd generation network, CDMA (for data), UMTS and EDGE, enabling voice, data and video transmission. O2 Czech Republic is also a provider of ICT services.
ONO was a Spanish broadband communication and entertainment company, delivering integrated telephone, television and Internet services to its residential customers. In this segment, it has 3.7 million services contracted and over six million users.
Sure, a trading brand of Batelco, is a telecommunications company in the Isle of Man, Jersey, Guernsey, the Falkland Islands, St. Helena, Ascension Island, and the British Indian Ocean Territory. Sure is the largest tri-island mobile operator across the Channel Islands and Isle of Man.
Cable & Wireless Communications Ltd operating as C&W Communications is a telecommunications company which has operations in the Caribbean and Central America. It is owned by Liberty Latin America and is headquartered in Denver, Colorado, US.
Telefonica UK Limited, trading as O2 (stylised as O2), is a British telecommunications services provider, headquartered in Reading, England which operates under the O2 brand. It is owned by VMED O2 UK Limited, a 50:50 joint venture between Telefónica and Liberty Global. O2 is the UK's largest mobile network operator, with 23.8 million subscribers as of May 2023.
Gibtelecom is the largest telecommunications provider in the British overseas territory of Gibraltar. Its headquarters is located on John Mackintosh Square.
Telefónica Germany GmbH & Co. OHG (German pronunciation:[teləˌfɔnɪkaːˈdʒœːɐ̯məniː]; also called Telefónica Deutschland ) is a provider of broadband, landline and mobile telecommunications in Germany. The company trades as O2 (typeset as O2).
Cerillion is a provider of billing, charging and customer management systems, based in the UK. The company was founded in 1999, focusing on a range of industries including telecommunications, finance, utilities and transportation.
£79.3 million (2014) [2] 
