Re: Any way to use att's data plan with HTC Desire ?
I posted the solution above. You need to manually enter ATT's APN info (basically the settings for ATT's data network). Additionally, the phone needs to be SIM-unlocked, if its locked to the India carrier. There are various ways to do it. One way is paid unlock services (around $10-20) on places like eBay. There may be free ways to do it yourself by rooting the phone, but I'm not an expert on this particular phone. You can research at a placed called XDA forums.