When thinking about which smrtDialer plan you want to sign up for, remember that it's all about call volumes. The multi-line dialer allows more numbers to be called in a period of time because it can ring many numbers at the same time.
The single-line dialer will dial one number at a time.
The multi-line dialer will dial up to 4 lines at a time.
Remember that the multi-line dialer is not all-or-nothing - you set the number of dialers to use during each call session. It typically depends on the type of calling and the origin of the call list that determines which is the best strategy and smrtDialer subscription for your team.