I just changed to a 64K SIM card and now I can't roam on T-Mo anymore. I can only use the blue network. I go to my network selection menu, select T-Mobile and it doesn't let me register. However, I think those with Cingular 32K SIM cards can still use T-Mo towers. If you have a 32K SIM card and you are in North NJ or NYC, can you use the T-Mo network? I really don't miss T-Mobile coverage that much (who would in this area? ) but it is just nice to know it is there as a backup just in case one day the Cingular blue network misbehaves which has happened a couple of times here. Note: You can find out which towers you are using by dialing #121. If you get a recorded message saying that "your call cannot be completed as dialed", then you are using T-Mo towers. However, if you get a greeting from "Voiceinfo", then you are using blue towers.