Display Name, User Name, Password and Domain are all required.
Register with domain can be checked if you wish to receive phone calls.
Outbound Proxy is optional. If it is blank, it would be the same as the domain IP address.
WIFI. When is checked, BlackVoib uses WIFI to connect to server. Other OTA is used.
STUN Server. Optional, but needed for most setups. This field is only left blank only if your device is in the same subnet as your SIP server.
APN. It would usually work went left blank. However, sometimes you do have to specify the APN. I don't have all the carrier APNs. But for AT&T, the APN is wap.cingular. You can also find these info on the net by googling them.
This link has good info on APNs http://www.blackberryfaq.com/index.p...N/TCP_settings