Hello. I bought an LG Optimus F3Q for my wife because she prefers the slide out keyboard. I checked that it is compatible with T-Mobile 4G first. The phone does receive a good 4G signal, however what happens is that if it doesn't receive a good 4G signal, it will drop to 2G. That's fine, but it will not go back to 4G when a strong 4G signal is available again. The only way I can get it back to 4G is to search networks and choose an AT&T signal then search again and choose T-Mobile RAT:LTE. When searching, available networks are T-Mobile LTE and GSM; AT&T LTE, WCDMA and GSM; Verizon LTE. When searching networks with my Alcatel phone, it sees T-Mobile 4G, 3G and 2G; AT&T 4G, 3G and 2G; Verizon 4G. So the LG doesn't see the T-Mobile 3G signal. I've read that if a phone is on 2G (GSM) and it doesn't see a 3G (WCDMA) signal it won't look for a 4G (LTE) signal. Is that why the phone doesn't go back to 4G? I've tried all the preferred network type options by dialing *#*#4636#*#*, but none will make 2G go back to 4G. I can force it to 4G only but then I get no signal at all if 4G isn't strong enough (like in the house). Any suggestions?