You may configure "Application Dial Rules" on CUCM to strip the digits.
CCMAdmin > Call Routing > Dial Rules > Application Dial Rules.
To make sure dial rules populated to CUPS, run the CLI on CUPS: "run sql select * from applicationdialrule". Restart SyncAgent if not see dial rules populated.
Restart CUPC to get the updated dial rules.
Michael
http://htluo.blogspot.com