Create a URI for both Inbound and Outbound, using Auto for the Local URI Display and Content, and Contact Display and Content.
Create a 2nd URI with Use Internal Data for those settings.
Use the SAME Incoming Group for both URI's, but DIFFERENT Outgoing Groups.
Route your calls through an ARS that uses the Auto URI, and the number to be sent will be whatever you specify in the Number field, like NS111222333. Or don't specify any CID and IP Office will match the outgoing CID with the user's Incoming Call Route (assuming they have only ONE DID). This behaviour is the same as a traditional PRI
Route your calls through an ARS that uses the Internal Data URI, and IP Office will pull the CID from the SIP tab of the User.
I typically have THREE ARS tables, one to use Internal Data, one to use Auto and specify the CID, and one to use Auto but not specify the CID. Use User Rights to determine which ARS the user gets sent to, or use System Short Codes of 9N for one table and 8N for the other.