Macworld’s Dan Moren tracks down the picky details surrounding T-Mobile’s announcement that it will start selling the iPhone (the 4, 4S, and 5) in the United States on 12 April 2013. Notable facts about T-Mobile’s move include unsubsidized hardware for down payments plus monthly charges, a $50 per month unlimited plan (for talk, text, and data, with a 500 MB cap on 4G data, which includes tethering), and simultaneous voice and data (offered by AT&T currently, but not Verizon or Sprint). follow link
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T-Mobile to Sell iPhone Starting 12 April 2013
A little confused by your last statement. Do you really mean simultaneous voice/data offer by AT&T, but NOT Verizon or Sprint?
Sorry, missing NOT, now added... You're correct. AT&T allows simultaneous voice and data, but Verizon and Sprint do not. Apparently T-Mobile will (which isn't surprising, given that they're using GSM).
Just verified with T-Mobile that the iPhone 5 will not support T-Mobile's Wi-Fi Calling feature, which is a bit of a bummer. Other sites are suggesting that it might eventually appear for the iPhone.