Zoom Phone users Ability to call out without a Dialable number assigned to their account

I have a need to establish a internal extension number that can make outbound calls and forward calls to an external number without the assignment of a DID number for the user. Zoom Phone Pro Unlimited assigned but when an external number is dialed it gets blocked saying the number cannot be reached.  When I assign a DID number from spares the user can call out. Is there any way to have outbound calling without a DID being assigned to the account