What is a pool of numbers?
A pool of numbers is a group of numbers that you can select as source.
The main benefit of selecting a pool of numbers when creating a campaign (instead of Your Number) is that the system will cycle through all your dedicated numbers and pick a different one every time.
This is not for everyone, but very convenient for companies that need to track responses from the same contact for different campaigns, or want different campaigns to go out from different numbers every time.
What's the difference between a shared vs a dedicated pool of numbers?
The Shared Numbers Pool is the pool of numbers owned by SMS Central and shared by all SMS Central users. It's a different number every time, but it's not exclusive to your account.
Dedicated Numbers Pool is the pool of numbers owned by you and shared only by users in you account. The pool contains those numbers you previously purchased.