British Telecom today announced it has struck a deal with One2One owner Deutsche Telekom over the sharing of mobile phone masts in the UK.
BT Wireless and T-Mobile International -the two firms' mobile businesses - will also cooperate on the development of next generation (3G) phones.
Mr Peter Erskine, BT Wireless chief executive, said the alliance was a "pioneering agreement" which would save his operation up to £1.3 billion in 3G costs over the next decade.
BT Wireless forecast a 20 per centreduction in the number of new masts and base stations likely to be required by BT following the One2One tie-up.