I connect to the internet through Bluetooth and my t68i. But although I can receive calls and text messages during the GPRS connection, it was a pity that I couldn't turn on Address Book functionality. A quick look into BluetoothMonitor from the Developer Tools package (in Applications -> Utilities -> Bluetooth) gave the answer: both default modem and Address Book uses the same channel ID (1), which results in conflict. So, I opened Bluetooth Serial Utility in /Applications -> Utilities, and added a new port. I called it "Bluetooth-Serial-2" or whatever:
- Port Direction: Outgoing
- Select Device... (your phone name) > Serial Port 2
- [yes] Show in Network Preferences
- Port Type: Modem
Then I opened Network Preferences and it asked me to add the new port. I made some cosmetic changes -- renamed it to "Bluetooth modem" and disabled the original "USB Bluetooth Modem Adaptor" in "Network Port Configuration." Then I set up the PPP section (remembering to uncheck "Send PPP echo packets" in PPP Options...) to my former values, as well as Bluetooth modem (thanks to these GPRS scripts which works great!)
And now it works, because it uses RFCOMM Channel ID: 5 now. When typing this, I received some SMSes and a phone call and they popped up! I also tried iSync (which uses channel 11) and first I got some error messages. However, I believe it was because I was downloading a large file at the same time as for the second and third tries, everything was okay.
I hope that this helps somebody too. I haven't found any other resources with this problem. I also don't know what are those security (authentication and encryption) options in adding the serial port?

