I just got the MTK6582 SM-G900F Samsung S5 clone, it says it has WCDMA support for 3g but I only get 2g on T-mobile in USA. The baseband is reading with a 2013 date and i've seen roms with a 2014 date. I've been able to flash the roms but the baseband/modem never change. What is the correct way to flash the modem??
Thanks in advance
Hello dboykin, you can't change the frequencies to anything other than what the hardware is compatible with. It's highly unlikely your clone has 1900 or 850/1700 which is required by T-Mobile and their MVNO.
The best you can hope for is that it has 850 and then you would be compatible with AT&T and AT&T MVNOs in *some* areas (much of AT&T is also on 1900 now).
Sorry for the bad news. My advice would be try a friend's AT&T SIM and see if you can catch 3G in your area. You can first check Mobile Uncle (download from Play) "Band Mode" to see what frequencies the software supports. If you don't see 850 listed there, you're out of luck.
I'm just echoing what cookiedough already said. Your phone probably doesn't have the hardware to support T-Mobile USA's 3G network. Sorry, man.