The new iPhone 4S has 2 antennas: both GSM and CDMA. Is there a chance that if I, who am an AT&T customer, buy one of these, that I would be able to use it in areas that are CDMA only? AT&T is GSM only. I have two locations out of town that I frequently visit that have ZERO GSM / AT&T coverage, but get full coverage to Verizon and US Cellular, both CDMA networks.

  • 1
    This is a great question, but I suspect impossible to answer, since the phone won't be available for another week. My guess is "no", since AT&T would've never had a reason to have a roaming agreement with the CDMA carriers. Now if the phone would let you set it up on AT&T and Verizon (and pay for both), that would be interesting.
    – bwall
    Commented Oct 4, 2011 at 19:21
  • He'd need a dual-SIM phone to be on both... Or else constantly switching the SIM back and forth Commented Oct 4, 2011 at 19:31
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    CDMA doesn't use SIMs, so that's not true. Only GSM (AT&T/T-Mobile in the US) uses SIMs. Verizon/Sprint do not.
    – bwall
    Commented Oct 4, 2011 at 19:37
  • The CDMA phones will use a GSM micro SIM while roaming internationally and shift encoding schemes to connect via GSM when needed.
    – bmike
    Commented Oct 4, 2011 at 20:26

1 Answer 1


No. CDMA will only work of you buy and activate your 4S device onto a CDMA carrier.

The FAQ shows that when you activate the phone it will choose one technology for coverage in country. GSM Registered phones will roam on GSM as will CDMA phones. Sprint should work in 35 unnamed countries and Verizon in 40 at launch.

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    Yep, bmike's spot on. While technically the phone supports the network protocol, it has to be registered with the respective carrier. GSM uses a SIM card to register the device with the carrier, so all you need is the card from a respective carrier to connect. CDMA requires that the device be registered.
    – user10355
    Commented Oct 4, 2011 at 20:36
  • Thanks. The FAQ wasn't up when I originally asked the question ;)
    – Joshua
    Commented Oct 4, 2011 at 21:32

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