There is a well know issue with SNR and Call forward all when the calling number is not a DID assigned by the Telco.
Post here your debug isdn q931 to confirm if it is the case. Most likely you will have to convince your Telco to let you do this or implement translation rules on the voice gateway to override the calling number.
These are the paths to get to each CCX logs through CLI. They may be helpful if you are having issues accessing RTMT or downloading logs through it.
If you want to download them you have to prefix "file get " and you can add one of the options (re...