Channels (sometimes referred to as sessions or trunks) are the network capacity that has to be purchased in order to receive calls on your virtual phone number (also referred to as DID’s). Each channel allows for one concurrent call.
There are four trunk zones available: Zone A, Zone B, Zone C, and World Zone. Zones A, B, and C each allow you to combine numbers from different countries around the world. Every zone’s call capacity can be shared by numbers from countries within that zone. You can add numbers from any country using the world zone networks