said by RARPSL: said by iFail 5G: said by HaloFans:
What's the frequency that T-Mobile uses for phone calls and text messages?
It depends on which network, T-Mobile like AT&T is essentially running two different networks. If you are on the GSM network, then 1900mhz, on UMTS/HSPA+ its AWS 1700/2100
The UMTS/HSPA+ is their 3G/4g DATA (ie: Internet) Network. The Phone and Text are 1900 Mhz (which is why the iPhone can work as a PHONE with T-Mobile SIMs/Mini-SIMs). They also share the same frequency (I do not remember which it is) as AT&T's EDGE Network so the iPhone falls back to EDGE for Data usage when not in an T-Mobile (or T-Mobile Roaming) area.
Huh? No, GSM is their *legacy* network which runs on the PCS 1900mhz block, AT&T also runs GSM in 1900 and 850mhz. Both carriers have chosen the next upgrade path as UMTS/HSPA+ which for AT&T run's on 850/1900,. T-Mobile's run's on AWS 1700/2100 mhz.
UMTS/HSPA+ carry's voice and SMS + data all at the same time. If you are connected to UMTS then you are not connected to GSM/EDGE at all.
When you put a T-Mobile SIM into an iPhone it looks for UMTS on 1900/850mhz but cannot find it so it reverts down to T-Mobile's older GSM network.