Currently for users with "assigned data only" access you can only assign one phone number for them to use. The other option is allow access to "all records" then the can outbound call from any number within the sub-account.
For any company who wants to provide a user with multiple numbers this is extremely limiting. We have reps calling different states and need local numbers for customers to pick up the phone. There are a number of other use cases but it is quite problematic.
There are two solutions:
  1. Allow users to be assigned multiple numbers via admin panel.
  2. Allow users access to all numbers without requiring access to all records.