We heard that T-Mobile USA was looking to dabble in the low-end arena with $50 unlimited voice plans, and sure enough, the carrier has gone live with 'em in the City by the Bay. In a surprise move aimed to rival similar plans from lesser known providers such as Boost Mobile, T-Mob is offering "loyal customers" the option to move to a $50 flat-rate calling plan. In order to get the offer, you must be located in San Francisco (for now, anyway), have been a subscriber in good standing for at least 22 months and want
