i've got an iPhone 3G running firmware 2.2.1 jailbroken and unlocked with Baseband 02.28. Provider: O2 Germany.

Since two days, i can't make any outgoing calls anymore. Everytime i dial it says "call ended" - "call failed". Besides the "show my caller id" switch in setting->phone ist toggled on but inactive which means i can't toggle it. But i can still receive calls, send and receive SMS and surf the internet via 3G an WiFi.

What did i do shortly before this occured?

Nothing remarkabel! Except installing Swirly MMS from the Cydia-Store.

What did i do trying to fix the problem?

I tried several SIM-Cards of E-Plus, T-Mobile and O2. Non of them worked in the iPhone but did work in a different phone.

I restored the iPhone with my jailbroken 2.2.1 Firmware an a jailbreakoken 2.2 firmware.

I restored the iPhone with an unchanged 2.2 Firmware with an T-Mobile SIM-Card (official iPhone provider here in Germany).

Sadly, nothing worked. My assumptions are:

1. Hardware failure. But how can it be that this affects only outgoing calls?

2. Software failure. Is it possible taht Swirly MMS or anything else changed something in my baseband?

I hope you professionals can help me out because i don't want to send my iPhone to apple an have the firmware replaced by a nice unlockable 2.2.1 with baseband 02.30 (bootloader on my phone is 6.0.2).

Thank you!