HOW TO Unlock an AT&T HTC TyTN II

Does anyone knows how to get the code to unlock the HTC TyTN II ?

Any Suggestion?

I have a ATT Tilt and I just put a Nextel sim card in it and unlocked it. But now it says there is no service. I assume there is a network issue here. I have tried to look up the nextel network in the list of networks but its all foriegn to me.

Also I will be transferring to T-mobile and want to make sure it works for that too. can anyone give some advice.

The Att tilt is GSM version and your nextel chip is CDMA which arent compatible

here is specs for tilt there is nothing stating CDMA compat

# Quad band GSM / GPRS / EDGE (GSM 850, GSM 900, GSM 1800, GSM 1900)
# Tri-band UMTS/HSDPA/HSUPA (UMTS 850, UMTS 1900, UMTS 2100)