Sharon has a Verizon cellphone but wants to get her old AT&T iPhone 4S added to the plan. Verizon said they can't add that phone to their network, though. Leo says back then, AT&T and Verizon phones only worked with either GSM or CDMA technology. If the phone was newer, like an iPhone 5S or iPhone 6, she could do it because they are called "world phones." She may need to unlock it. But the 4S predates the era of iPhone world phones, and it won't work.
Rick says that he hears that with Sprint, if they upgrade to the new iPhone, they won't be able to talk and surf at the same time. Leo says that he can on AT&T and Verizon, though. Verizon moved over to Voice Over LTE and Leo thought Sprint was moving that way too, but apparently they haven't. T-Mobile will also work. Any GSM network will do it, and Leo suspects that Sprint will eventually go that way.
Steve was gifted an iPhone 4 and the carrier is verizon, while his carrier is T-Mobile. Leo says Steve can't use it because the iPhone 4 is a CDMA phone while T-Mobile uses GSM. So it's essentially apples and oranges. It's just not compatible. The new iPhones though are "world phones" and can use various SIMs. Leo says that's where it's going, especially for Verizon because they were ordered by a judge to stop locking their phones to a carrier.
Paris has an iPhone 5 and he wants to unlock it. Leo says that on Sprint/Verizon, the iPhone is a CDMA phone. But if he unlocks it, he can buy a SIM card from AT&T or T-Mobile and it should work.
John wants to know if an unlocked iPhone 5 from Verizon would work when traveling to Europe. Leo says that Verizon is a CDMA carrier, but the iPhone 5 is called a "world phone" because it works with both CDMA and GSM. Verizon set it up so that while CDMA is locked to Verizon, the GSM radio is unlocked for any carrier. One of the chad mods recently went to Japan and it worked great with a prepaid SIM.
Don just got an iPhone from Verizon and doesn't know if he needs the SIM chip. The chatroom says that the SIM chip is for the LTE data plan.
Verizon also sells phones that can be used all over the world and the SIM port is for that purpose.
Bob wants to know where the best place to get a SIM card is for his Sprint iPhone when he's in Europe. Leo says that Sprint uses CDMA, not GSM, which is what's required for a SIM card. However, the iPhone 5 is a world phone, meaning it has both CDMA and GSM options. With Sprint, however, the GSM slot is locked. He could go to Sprint and explain to them that he's going to Europe and ask if they'll unlock it. Then he could buy a local SIM while he's in Europe. The chatroom says that if he's a customer in good standing, Sprint should unlock it.
Pronav bought an iPhone 5 on Sprint, but hears that Verizon iPhone’s comes unlocked. Would the Sprint iPhone 5 be unlocked as well, since it’s the same phone? Leo says no. Verizon chose on their own to unlock the iPhones that come through them. Leo believes that going forward, this will likely become the norm though. Will he be able to use his Sprint phone on another service when his contract is over? An eager rep at Verizon may be able to do it by unlocking it with software.
Yoni is traveling over seas and he wants to know if he could forward his Virgin Mobile calls to Thailand. Leo says that Yoni's CDMA phone won't work in Thailand at all. So he recommends buying an unlocked, GSM phone that has a SIM card and then buy a local phone. Leo's first recommendation was to use Google Voice for forwarding the calls, but it won't work to overseas numbers, it is US-only. For this reason, it may be worth contacting Virgin Mobile to see if they have a world phone.
Leo says that there's a good chance he won't be able to use it all. It's a CDMA phone, and most cell networks overseas use GSM technology. If he upgraded to the iPhone 5, he'd have no problem. The Verizon iPhone 5 comes unlocked and is a world phone, so Eric could buy a local SIM card and use data locally.