3CX and CM Phone

Finally, I got it worked!

Worked means:

1. 3CX Free Edition installed, up and running
2. My Nokia E71 and N82 are able to work as extensions
3. CM Phone account able to work as VoIP provider

The following features are enabled:

1. Inter-extension calls
2. Extension to PSTN calls
3. PSTN to extension calls
4. Voice mail
5. Check voice via extension and PSTN

Great!