Mobile will sell more than 100 smartphone models with a built-in feature that taps into Wi-Fi networks to make phone calls and send texts when customers can't connect to the wireless carrier's cellular network. The program announced Wednesday represents T-Mobile's latest attempt to lure wireless subscribers away from three larger rivals, Verizon Wireless, AT&T Corp. and Sprint Corp. Over the past 18 months, T-Mobile has shaken up the industry by replacing two-year contract commitments with monthly installment plans to pay for smartphones and lowering the cost to upgrade device and stream digital music.