Rent a phone number for another user
The Request an internal phone number
endpoint accepts a new optional assign_to field, holding the IDs of the users
the new phone number is assigned to.
When assign_to is omitted, the phone number is assigned to the user making
the request, as before. Assigning it to anyone else requires the
Manage Team Phone Numbers permission, and every user must be an active
member of the organization who is allowed to make calls.