Its Simple
GSM works far better than CDMA for one simple reason — the broadcast band it uses is more reliable. Nonetheless, among those that tout they use GSM, AT&T (prepaid counterpart Cricket) and T-Mobile (prepaid counterpart MetroPCS), T-Mobile/MetroPCS dropped service repeatedly in recent tests. MetroPCS uses IP6 addressing over T-Mobile’s network. Nonetheless, Verizon, despite their use of CDMA, works well in most East Texas areas.
It would be hard to generalize, but in actual tests around the East Texas Lake Areas, MetroPCS phones dropped everything from cell service, to texts, to data during cloudy days. Sprint phones and its counterpart Boost Mobile are expected to perform equally poorly in outlying East Texas areas. While AT&T and Cricket might be better alternatives in some cases, there is always an expense trade-off. Data plans vary between these companies but the main advantage any company will have over another is, up-time percentage: Weather sometimes interrupts service–but a few clouds should not drop service entirely for any noticeable length of time.
A Little More
A feature of some cellular services is the routing of calls and texts over the same bandwidth as its data stream. This means very annoyingly–no data access also means no texting. GSM uses two different bandwidths, one for calls and texts, and the other for data. This means you might temporarily hit a spot where you are without data (maps, music, web browsing), but your phone and texts will still generally work. Photos sent via text do not actually go via text–because by definition texting is, well, text. Thus, pictures always use data as multimedia or email messages, and may not go out at all in areas with poor service.
Here is a table extracted from https://techspirited.com/gsm-vs-cdma comparing GSM and CDMA technology. I have added a column to weight for usefulness in sparsely populated Rains County and adjacent rural areas.
| Topic | GSM | CDMA | Rains County |
| Companies | ATT, Cricket, T-Mobile,Boost, Europe | Sprint,Verizon,US Cellular | GSM more available in rural areas, however carriers are recently abandoning 3G networks, and now support only 4G and 5G phones. |
| % Use | 50%, 3.7 billion | 5%, 350 million | Roughly as of 2016; others LTE 12%, HSPA 29% |
| Call Quality | Good | Better | Insignificant difference overall |
| Carriers | Flexible | Hardwired | GSM users may switch SIM cards to compatible networks CDMA users must switch phones to use a different network |
| US Coverage | Good | Good | GSM slightly more available in rural areas |
| Emergency | 112 | Varies | 112 is recognized as emergency help number worldwide on GSM networks only |
| Battery | Better | Good | CDMA uses more energy |
| Speed | Varies | Varies | Both technologies run neck and neck as far as real-user experience is concerned. Speed is not a significant factor for calls and texts. It only affects data such as downloads and sending pictures. |
| Roaming | Free | $$$ | GSM is more widely used, and usually free roaming |
| Inside Buildings | Good | Good | Metallic buildings interrupt all sorts of wireless communications. 5G networks are notably less accessible than 3G and 4G phone networks |
MetroPCS, AT&T, Cricket, Verizon, T-Mobile, Boost, and Sprint are trademarks of their respective companies.
