I am a little confused here. It is listed as a quad band phone with 3g but the review lists 2 other bands (GSM quad band world phone 850/900/1800/1900MHz bands with EDGE. HSDPA 3G on T-Mobile's US bands 1700/2100MHz). What does this really mean? Will it work on other networks with 3g such as AT&T or Verizon? I am looking at buying this phone direct from T mobile just to use it on other networks. Will this work