O2 has signed a 10 year contract with Virgin Media that will help the network deal with the data demands of 4G customers, when the service launches this summer.
The setup will see O2 base stations plugged into Virgin's superfast fibre optic network - something which O2 says will boost mobile broadband speeds and reduce network congestion.
The partnership will provide O2 with additional capacity so it can meet the needs of bandwidth heavy media such as HD video streaming and online gaming.
Telefonica's UK chief technology officer Adrian Di Meo said, "With our 4G network launching this summer, data growth will only continue to rise and this new fibre agreement with Virgin Media Business will give us the rock solid foundation we need."
The UK's remaining 4G operators, EE, Vodafone and Three, have already signed similar contracts to use the broadband provider's 'synchronous Ethernet mobile backhaul service'.
"Backhauling data is absolutely critical to ensuring that mobile operators are able to provide customers with fast and reliable data services," said Virgin Media Business director of mobile and broadcast George Wareing.
"We're able to arm networks with the extra capacity needed to make sure that customers don't experience slow speeds because of data bottlenecks, and that they're prepared for the future of 4G services and beyond."