Two kinds of number
You can rent numbers through Fuse, or add a number your business already owns. They are not equivalent.
Rented numbers are the fuller option, because Fuse manages them end to end and ties US numbers to your business profile. A number you already own is worth adding when your contacts recognize it.
Which number a call goes out on
For single dialing you can pick a specific number yourself, or hand the choice to Fuse. Parallel dialing always hands the choice to Fuse, so call volume is spread across every number you have available. When Fuse chooses, it looks for continuity first. If the contact has answered a call from you before, including by voicemail, Fuse reuses the number from that most recent answered call, so they see a caller ID they have seen from you already. Only when there is no number to reuse does it fall back to the automatic mode you selected, either Randomized Area Code or Closest Local Area Code.A number rated unsatisfactory is left out of automatic selection for new contacts. Fuse still reuses it for contacts who have answered a call from it before. See business registration and number health.
Where to go next
Your phone numbers
Renting a number through Fuse, or adding one you already own.
How Fuse picks a number
Contact continuity, and the two automatic modes.
Business registration and number health
What registration buys you, what it cannot promise, and what pauses dialing.