VZW/Sprint iPhone 4S Weird Roaming behavior?

[gfunkdave]

I searched around and didn't find anything. I'm hoping people here will know.

I have a VZW iPhone 4S. I understand it will only work on VZW in the USA.

If I go to a country that has a CDMA network - like China, Israel, etc - I've heard that the 4S will only latch on to the CDMA network, and will ignore any GSM networks it finds. In addition, the VZW 4S does not have the menu item under Settings - General -Network to manually pick a mobile network.

In addition, the thread I started on Apple's discussion boards seems to say that, in such a country, if I put in a local SIM, my phone will still insist on CDMA roaming through my VZW account.

Is this true? What are the workarounds? I can't imagine this is actually how VZW wants people's phones to work.

Thanks!

[n2jtx]

With my Sprint 4S, which is also CDMA, I have no issue like you described. When I am in Canada, I put a Rogers micro-SIM in my phone and I run with UMTS. No CDMA roaming attempts. In fact, back here in the U.S. I can put my old Rogers mini-SIM that I cut to micro-SIM size in my phone and it will switch to GSM/UMTS mode. I get "No Service" because it cannot register with either AT&T or T-Mobile due to having an inactive SIM. Not until I pull the SIM out does the phone revert back to Sprint.

[gfunkdave]

Interesting. OK, I wonder if it might be a Verizon-specific thing.

Next question: is there a way to enable the Settings -> General -> Network -> Manual network selection option in the iPhone 4S that Verizon sells? Would a jailbreak accomplish this?

[n2jtx]

Interesting. OK, I wonder if it might be a Verizon-specific thing.

Next question: is there a way to enable the Settings -> General -> Network -> Manual network selection option in the iPhone 4S that Verizon sells? Would a jailbreak accomplish this?

I only see that settings option when I install a foreign SIM. It sometimes remains after I pull the foreign SIM out but it is hit or miss and eventually disappears. Likewise, I checked for a PRL update yesterday with Sprint's ##UPDATE# code and after the phone searched for towers (not sure why - there was no PRL update) that option appeared and was set to manual. However, there were no carriers listed and it went away after about a minute. As far as I know (I am more familiar with GSM/UMTS) there is no way to force roaming when running CDMA mode.

[bsweetness]

The inserted SIM card appears to be what triggers whether it will connect to a CDMA or a GSM network if the phone is unlocked. Having the SIM slot unlocked is the important part of course. With an unlocked Verizon 4S, if you're outside of the U.S. and put a foreign SIM card in it, you'll have no problems connecting to that network, even if a CDMA network exists in the country. If your 4S is not unlocked, the phone will connect to whichever partner Verizon wants you using in any particular location, whether it is CDMA or GSM.

I've used my unlocked Verizon 4S is China and throughout Europe, and it's never tried to connect to a CDMA network when I have a foreign SIM inserted.