GSM, WCDMA, and LTE are the three main cellular technology generations that determine which carriers and markets a phone is compatible with:
- GSM (2G), legacy second-generation cellular standard, still used for fallback voice and SMS in many markets.
- WCDMA (3G), third-generation, used for voice and basic data; being decommissioned in many markets.
- LTE (4G), current high-speed data standard, the primary network for almost all modern smartphone use.
- 5G NR, current-generation, layered on top of LTE in most networks.
Within each generation, regional band configurations determine compatibility. The same iPhone model has different US, EU, China, and Japan variants because each region uses different LTE bands. A US-spec iPhone 15 Pro (model A2848) has different LTE band coverage to the EU-spec variant (A3104) and the China-spec variant (A3104 with eSIM disabled). Buying the wrong regional variant for your market can leave the phone working only on partial bands or limited carriers.
Wholesale buyers should always check the model number against the destination market's carrier band requirements. Apple's iPhone Compare tool and GSMArena's database provide authoritative band specifications by model.