As msouva said, DID Service form is one place to look... a lot of systems that have been in place for a while may not use this though, it could be a system speed call entry (if it is, you really should migrate it to using the DID Service form). You can verify this be looking in the Trunk Attributes assigned to your trunk, if it says DID Service - Yes then it is using the DID Service form, if it says DID Service - No it is likely using the system speed call form (this does not mean you don't have DID's, just if it uses the DID Service routing form or not).