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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.

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migrated from Oct 4 '11 at 19:44

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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 Oct 4 '11 at 19:21
He'd need a dual-SIM phone to be on both... Or else constantly switching the SIM back and forth – Canadian Luke Oct 4 '11 at 19:31
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 Oct 4 '11 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 Oct 4 '11 at 20:26
up vote 6 down vote accepted

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 Oct 4 '11 at 20:36
Thanks. The FAQ wasn't up when I originally asked the question ;) – Joshua Oct 4 '11 at 21:32

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