The OS installed has nothing to do with what services are pushed to the device. That's the sim card's job.

Go to the Phone app. Then click the wheel and select Options and go to Smart Dialing. Enter your area code in there. You may still need to dial the area code, though.

You can use wap access but you need to go to Options >Advanced Options >TCP and enter TMo's apn there.

apn:wap.voicestream.com
username
password

username/password stay blank.