BT Group plc (LSE: BT.A, NYSE: BT) is a global telecommunications services company headquartered in London, United Kingdom. It is one of the largest telecommunications services companies in the world and has operations in more than 170 countries. Through its BT Global Services division it is a leading supplier of telecommunications services to corporate and government customers worldwide. Its BT Retail division is a leading supplier of telephony, broadband and subscription television services in the UK, with over 18 million customers.

Its primary listing is on the London Stock Exchange and it is a constituent of the FTSE 100 Index. It has a secondary listing on the New York Stock Exchange.

BT is the world’s oldest telecommunications company. The company's origins date back to the establishment of the first telecommunications companies in the United Kingdom. Among them was the first commercial telegraph service, the Electric Telegraph Company, established in 1846. As these companies amalgamated and were taken over or collapsed, the remaining companies were transferred to state control under the Post Office. These companies were merged and rebranded as British Telecommunications.

Source: Wikipedia