GSM Handsets: Technical Information

Hello:

I am looking for a resource on or offline that I can get comprehensive
technical information on GSm hadsets. I have tried manufacturers sites but
they all tend to be consumer oriented.

The sort of infomation I am trying to get involves, the handset class, the
specific freequency bands, the power output, power consumption, control and
test mode codes for the handset, etc.
Please help.

Thanks.