The way we do this here is:
Under Trunks - Digital - ISDN - Outgoing Call Characteristics - DID Ranges for CPN Substitution. Open an index and select the DID Range (can be an individual extension number or a range - in your example you would put 111-118) and under CPN Substitution put the number you want to be displayed at the other end (eg 5555100).
Note that some carriers (all here in Aus, anyway) limit the number you can display to what is enabled on your line (say your line has a indial range of 5555100-5555199, you can't show the number 1234567, it has to be inside that range).
Next, go to the CPN Substitution form (just below the DID form) and in the controller module that your trunk is on, add the index you created into the DID Ranges for that module (they may already be in there, I know ours were).
We use this feature in the office so the main receptionist isn't taking all the business calls - each department has their own nominated number that appears when calls inside that department call out.