I purchased a samsung galaxy s2 on ebay. When I put my Tmobile SIM inside all I am getting is EDGE network. I have tried changing all settings but I can't get 3G or 4G network. I tested with swapping the SIM out with a friend's ATT sim card and I was able to get on to ATT's 3G network. I have a 2 year Tmobile plan and I feel I am stuck. Is there any app or any solution that will help me get onto Tmobile's 3G or 4G network. Being on edge network sucks as you all know Thanks for your help.