One important step in Campaign Creation is setting Phone Number Depth. This setting within the campaign represents how many numbers to dial per lead if lead records have multiple numbers associated with them.
When running a smrtDialer Campaign with a wider Phone Number Depth, the system will call all the numbers a lead has until one of them is answered. Once answered on a number, it will go on to the next lead.
If the calling agent still wants to call the rest of the numbers attached to the lead after one of their numbers was answered, they need to use the Wrong number filter.
Even if you are using a multi-line or a single line, the system will call all the numbers of the lead on the same line until someone picks up. This way, the lead will not receive multiple calls from multiple numbers, but the same smrtPhone number for each of the lead's attached numbers.