If the call processor is a CallManager server, then you check 'provide outside dialtone' in the route pattern config - If it is coming in on a T1 (pri or cas) to a router, then on the pots peer that will be matched on the way in, make sure you do not have 'direct-inward-dial' - I think it is on by default on CAS, so you would have to do 'no direct-inward-dial'.
Here is a tech note on one and two stage dialing, two stage is when dial tone is provided then digit collected:
http://www.cisco.com/en/US/tech/tk652/tk698/technologies_tech_note09186a00800e00d0.shtml
Mary Beth