BT Mobile customers will be able to have access to the high-speed data service in 20 major towns and cities across the UK.
The service is powered by EE's 5G network, which arrived in London, Edinburgh, Cardiff, Belfast, Birmingham and Manchester in May.
EE overtook Vodafone with the announcement of their 5G service.
BT Consumer CEO Marc Allera commented: "5G is going to give customers in the busy areas an uplift of 150Mbps on average and often more than that. This is a premium experience.
"We are confident that some customers will break the 1Gbps milestone. When we launched 4G in 2012, we were talking bout 12-15Mbps and hat was game changing.
"But it's not about peak speeds in peak conditions - it's about reliability. Our 5G strategy is demand led and focuses on the busiest areas of busiest cities. These sites make up eight per cent of our network sites but carry 20 per cent of our data traffic. These are the areas our customers need it most."
The first phase will last until 2022, when the newest technology will be available. Whilst the third phase will launch in 2023.
Vodafone on the other hand are offering 5G in Birmingham, Bristol, Cardiff, Glasgow, Manchester, Liverpool and London on June 3rd.
And by the end of the year, they are planning to launch 5G in Birkenhead, Blackpool, Bournemouth, Guildford, Newbury, Portsmouth, Plymouth, Reading, Southampton, Stoke-on-Trent, Warrington and Wolverhampton; a total of 19 cities.