Choose which of your numbers shows as your caller ID when you call from the VocPhone mobile app.
Tap your user name at the top of the app.

Your available numbers appear — every number the account owns except 1300 and 1800 numbers.

Select the caller ID you want to present, then tap Save.

When you call a colleague on the same account — by their extension or MyPBX short code — they see your internal (MyPBX) number, so internal calls are easy to recognise at a glance. If you don't have your own MyPBX number, they see your normal caller ID instead.