how to unlock Sony Ericsson W350

[evanjc]

I have the same phone:

22:38:07| TURN OFF PHONE!
22:38:07| Hold 'C' button on phone and connect phone NOW.
22:38:07| You have 30 seconds...
22:38:07|
22:38:15| Baseband ID: D000
22:38:15| Protocol Version: 3.1
22:38:15| Warning: IMEI name does not match GDFS name (IMEI:NULL GDFS:n/a)
22:38:15| ...using GDFS name
22:38:15|
22:38:15| Profiling SEMC phone...
22:38:15| Platform: PNX5230
22:38:15| OTP CID: 52
22:38:15| EROM CID: 53
22:38:15| EROM Color: Red
22:38:15| IMEI: 35623702xxxxxx
22:38:15| Phone ID: n/a
22:38:15| Region: n/a
22:38:15| CDA: n/a n/a
22:38:15| Firmware Version: n/a
22:38:15| EROM: n/a
22:38:15| Ready for operation!
22:39:02| Sorry, your phone is NOT SUPPORTED
22:39:02| Sendinging shutdown signal to phone...
22:39:04| Shutting down...

Does anyone tried to ask AT&T to unlock the phone? Or, can someone suggest which unlock service is cheaper and better?
BTW, can I upgrade the firmware before unlock the phone?