Ok thanks, I don't actually see the DID Translation form? We are running 7.2SP1.
Call Routing - Call Handling - Direct Inward Dialing Service
It only works if you have Direct Inward Dialing Service enabled in your Trunk Attributes for that trunk. Using it integrates several elements of the Service Details tab of User and Services Configuration, including DID Service Number and Use DID Number for Outgoing Calls (it automatically updates the Associated Number form).
Remember it's all or nothing... once you change your trunk attributes to DID Service, the System Speed Call form is not used.