Mobile phone operator Hutchison 3G has signed an agreement to lease network capacity from MMO2's BT Cellnet.
The contract will let Hutchison offer nationwide third-generation (3G) voice and data roaming services without a 2G network infrastructure of its own.
The companies would not disclose the value of the deal, but reports estimate that it will provide MMO2 with further wholesale revenues of tens of millions of pounds.
"This agreement is very important to delivering our service in the second half of next year," said Colin Tucker, managing director at Hutchison.
The company said that it will have 99 per cent population coverage in the UK for voice and SMS services.
Hutchison is one of five companies awarded licences by the UK government last May to run 3G mobile phone services, and is the only one that is concentrating on 3G alone as it was not an existing mobile player.
The telco plans to be the first 3G operator in the UK, launching services in September 2002 and offering subscribers web content via compatible mobile phones.
But 3G coverage will only be available initially in large population centres, obliging Hutchison customers to access existing 2G networks to make calls to areas without 3G access.
Some parts of Atacama have not received rainfall for 500 years - but a sudden deluge of water upset the Desert's delicate biological balance
Spitzer Space Telescope could not spot Oumuamua, suggesting that it is actually pretty small
Greenland crater one of the 25 largest impact craters on Earth
This long-sought progenitor star was identified in an image captured by Hubble in 2007