The new name will be deployed when BT spins off its umbrella mobile division, BT Wireless, this autumn. The same name will be used for the division and the units it operates.
The company has so far denied that it is planning to rebrand the individual mobile operations when it rebrands BT Wireless, but it said, "these things are being kept under review constantly".
Although BT Cellnet is one of the UK's best-known mobile brands with 11.2m users, its market share is believed to be slipping. In the last 12 months, Orange, the UK's third-largest operator, doubled its customer base to 11m customers, adding 1.2m in the last quarter. BT Cellnet added 918,000 in the same three months.
However, both are still trailing Vodafone. Vodafone, which only netted 600,000 customers in the last quarter, has a UK customer base of 12.3m. The fourth-largest network One 2 One, including Virgin Mobile, added 656,578 customers, bringing its total to 8.98m users.