Forwarding incoming calls to external destinations on CME

The other day I was working on a setup that would forward an incoming call to an external destination using an ISDN BRI interface. This would come in handy if nobody’s at the office, but you don’t want to miss calls placed to the main number. Time and again my attempts were failing with:

Cause i = 0×82E46C – Invalid information element contents

Searching the Internets for this cause code didn’t yield many results, but I did find some documentation on the Cisco website: Call Forward from CallManager Express to an External Number Fails. CME might also use the original calling number for the inbound call as the calling number for the outbound call leg. To prevent this from happening, you can use outgoing translation rules. A likely indication that this might work for you would be:

Cause i = 0×829C – Invalid number format(incomplete number) 

This didn’t solve my problem. In the end it turned out to be the numbering plan type as somebody pointed out. I configured the following, which made it work:

interface bri 0/0
 isdn map address . plan unknown type unknown
!