The iPhone 4S is the first device produced by Apple that is a dual-mode phone. This means the iPhone can theoretically be used on any CDMA or GSM network, in any country. In the United States CDMA ...

For U.S. cell phone customers, AT&T and T–Mobile are GSM carriers, while Verizon, Sprint, and US Cellular are CDMA, taking into account updates in carrier policies and plans to close off networks.

For older (read: non-LTE) phones, you must take in account that Sprint and Verizon are on the CDMA network, and AT&T and T-Mobile use GSM. These two 3G networks are not compatible with one another.

Or your contract has expired and you want to use your existing phone on your new carrier. This article is geared towards the US and our set of carriers and rules. GSM Only! Unlocking applies only to ...

If you use AT&T, T-Mobile, or another GSM carrier, you can forward calls just by entering the phone number in the Settings app. Dave Johnson/Business Insider 4.

GSM uses Subscriber Identity Module (SIM) to keep user’s subscription information and phone book. GSM works by using data in SIM card to send and receive texts, make and receive calls, or access ...

if you're tempted to buy a 2G phone on Amazon, or bring one home to use on AT&T or T-Mobile GSM networks—don't. They won't work, even if the carriers say they will. Here's why.

Siemens, makers of GSM switching hardware and, in conjunction with BenQ, GSM phones, is saying that CDMA is on its way out in North America. Ummmm… Right. According to the peeps over at Siemens ...

Model A1633 and A1634 (iPhone 6s and 6s Plus), which it lists for AT&T and 31 other U.S. carriers—other all other GSM carriers except T-Mobile. Model A1688 and A1687 (ditto) for T-Mobile, Sprint ...

The Nexus 4 is a pentaband GSM phone, so you can use it on any GSM network. Two such networks exist in the US, but you have more than two options. Let’s go over what you need to know.

But Sprint is hardly alone in its exclusivity.

CDMA vs GSM is pretty much dead and over with. Any modern phone will fall back to support both if LTE/5G aren't available. Carrier specific frequency support is more a function of time than ...