GSM vs. EDGE vs. CDMA vs. TDMA

These standards are the reason some phones can't switch networks

The type of technology a wireless carrier uses (GSMEDGECDMA, or TDMA) matters when you buy or sell a cellphone. While selecting the right mobile phone service plan at your carrier of choice is important, so is choosing the right carrier in the first place. We examined the different technologies wireless carriers use to help you tell the difference.

Not all of the protocols in this article are still in use.

GSM vs EDGE vs CDMA vs TDMA

Overall Findings

GSM EDGE CDMA TDMA
Information stored on SIM cards. Based on GSM. May use SIM cards. 2G system.
Switching phones means only switching cards. Three times faster than GSM. Provider stores information. Predates GSM.
Most widely used, especially internationally. Used by AT&T and T-Mobile. Can't change phones without provider approval. No longer in use.
Switch SIM cards to use phone in other countries without roaming.   Used by Sprint, Virgin Mobile, and Verizon Wireless.  

For years, the two major mobile phone technologies, CDMA and GSM, have been incompatible competitors. This incompatibility is the reason many AT&T phones don't work with Verizon service and vice versa.

EDGE is a faster version of GSM, and TDMA is effectively obsolete. Therefore, TDMA is not a viable choice anymore. It effectively comes down to GSM and CDMA, with GSM beating out CDMA for user- and consumer-friendliness.

Speed: EDGE Has the Advantage

GSM EDGE CDMA TDMA
3G network. Three times faster than GSM. 3G network. 2G system.
Max speed of about 7.2 Mbps.   Only about 1 Mbps. No longer available.
Average speed of 2.11 Mbps.      

Both GSM and CDMA are 3G networks, but between the two, GSM is the faster option. CDMA shows an effective download speed of about 1 megabit per second, while GSM claims speeds of up to 7 Mbps. Testing has put the practical speed of GSM closer to 2.11 Mbps, which is twice as fast as CDMA.

EDGE is three times faster than GSM and is built upon that standard. It is designed to accommodate streaming media on mobile devices. AT&T and T-Mobile have EDGE networks.

User-Friendliness: GSM Is Easiest to Transfer

GSM EDGE CDMA TDMA
Uses SIM cards to store user data. Works similarly to GSM. Doesn't use SIM cards. Unavailable.
Transferring to a new phone means only swapping the SIM card.   Carrier must release or transfer user data to a new phone.  
Better for international use.      

GSM network providers put customer information on a removable SIM card. This approach makes it easy to switch phones. Just take the SIM card out of the old phone and insert it into the new one. GSM technology is widespread in Europe. Combine that with a phone with a removable SIM, and you have a phone you can use on overseas visits with a SIM change.

CDMA phones may or may not have SIM cards. User information is stored with the service provider, which must give its permission to switch phones. CDMA phones must be programmed with every carrier you use. When you switch carriers, the phone must be reprogrammed for that carrier, even if it's an unlocked phone.

Providers: Look for Your Favorites

GSM EDGE CDMA TDMA
Providers include T-Mobile and AT&T. Same as GSM. Providers include Sprint, Virgin Mobile, and Verizon Wireless. Incorporated into GSM.
More popular internationally.      

GSM is the world's most widely used cellphone technology, popular in both the U.S. and internationally. Cellphone carriers T-Mobile and AT&T, along with many smaller cellular providers, use GSM for their networks.

GSM is the most popular cellular technology in the U.S., and it is bigger in other countries. China, Russia, and India have more GSM phone users than the U.S. It's common for GSM networks to have roaming arrangements with foreign countries, which means GSM phones are good choices for overseas travelers.

EDGE is an evolution of GSM, so it has the same availability as that older standard.

CDMA competes with GSM. Sprint, Virgin Mobile, and Verizon Wireless use the CDMA technology standard in the U.S, as do other smaller cellular providers.

Since 2015, all U.S. carriers are required to unlock customer's phones after they fulfill their contracts. Even if you unlock your phone or to buy a new unlocked phone, it is either a GSM or CDMA phone, and you can only use it with compatible service providers. However, having an unlocked phone gives you a wider range of service providers to choose from. You aren't limited to only one.

TDMA, which predates the more advanced GSM technology standard, has been incorporated into GSM. TDMA, which was a 2G system, is no longer in use by the major U.S. cellphone service carriers.

Final Verdict

The quality of the phone service has nothing to do with the technology the provider uses. Quality depends on the network and how the provider structures it. There are both good and not-so-good networks with GSM and CDMA technology. You are more likely to run into quality concerns with smaller networks than with the big ones.