Hybrid calling is a function of could registered devices.
You could do one of two items to get an DID to the device as is:
1 - Register it directly to CUCM
2 - Setup a DN and associate it to a Remote destination (using a SIP pattern from the device), which that SIP pattern of course routed to the Expressway / VCS. VCS would need a search rule pointed back at the CUCM zone as well for outbound calling.