Telewest has teamed up with Ericsson in a bid to enter the fast-growing internet telephony market.

The cable TV provider, now the UK's largest cable operator and a thriving broadband provider, has signed a five-year deal with Ericsson to migrate its existing voice network to one based on VoIP.

The initial phase of the deal focuses on residential customers, who will be offered a voice-over-broadband service using Ericsson's Internet Protocol Multimedia Subsystem technology.

Telewest's phone network will migrate to VoIP using Ericsson's Telephony Softswitch.

Ericsson claimed that the ultimate aim is to provide a cheaper alternative to traditional landline calls, and to save Telewest's running costs.

"Telewest is already seeing the benefits from its investment in its network, " said Jacqueline Hey, UK managing director at Ericsson. "Our technology will provide gains [for Telewest] in network running costs and efficiency."