Yesterday's report of T-Mobile offering its existing customers in San Francisco a $50 unlimited national calling plan has been confirmed today from a more reliable source. The wireless provider is also trying to lure customers away from competitors by offering them a $135 credit if they come over to T-Mobile. The move is believed to be in response to Boost Mobile, a unit of Sprint Nextel, launching a $50 all-inclusive cellphone plan in January.

A T-Mobile representative says the plan is being offered to local customers who have been with T-Mobile for at least 22 months and hinted the plan may be extended across the USA. An analyst believes the deal will become available nationwide in the next few weeks. The new T-Mobile package also offers a bundle with voice, data and text messaging for $85, down from the previous $100 for a similar level of service.

As the plan is at least currently aimed at long-time customers, it is meant to keep users with T-Mobile instead of attracting new ones. As such, the plan is not likely to put pressure on rivals Verizon and AT&T to offer similar deals.