Call Queues allow calls to be queued whilst agents (members of a call queue) answer calls.
Calls do not go unanswered but are queued until an agent is available to take the call.
For example, you can define a group of 3 sales people, and have the general sales number route to a sales call queue. If all 3 sales people are busy, callers will be kept in the queue until the next sales person is free.
When you create a call queue, you also assign it a virtual extension number.
This will be the number used by the phone system to “address” the Call Queue.