Capi - outgoing dial hunt


I’m configuring Asterisk to make outgoing calls through AVM C4 card.

In capi.conf for every of the four ISDN interfaces I set group=1.

In extensions.conf I dial Dial(CAPI/g1/{$EXTEN})

I expect Asterisk to dial on first available channel. However, it tries to dial only on the last interface specified in capi.conf.
If it’s not available (for example, the ISDN cable is not plugged in), it doesn’t try the other interfaces.

Any solution?