T-Mobile's last expansion effort of 2012 is a big one: the carrier is today bringing support for the 1900MHz band to numerous major metropolitan areas including New York City, Boston, Detroit, and Philadelphia. Texas residents also stand to benefit from the enhanced 3G footprint, with Austin, Dallas, Fort Worth, and San Antonio also on the list. T-Mobile's generous expansion of 1900MHz band allows former AT&T customers to bring their unlocked smartphones to T-Mobile's network without experiencing a major drop in 3G data speeds — which has been the case in years past. The carrier has previously worked to lure iPhone owners away from competitors, though anyone with the iPhone 5 will lose access to LTE if they opt to switch to T-Mobile. To see the list of all 14 cities gaining extended coverage today, follow the link below to T-Mobile's site.