Suppose we have Queues A, B, C, and D that all have some sort of rules that might direct a call to Queue 1. The Agents on Queue 1 need to know where that call originated.
We have customers calling in to Brand X. We have a team of agents that answer "Thank you for calling Brand X, how can I help you?".
Separately, we have customers calling in to Brand Y, where we answer "Thank you for calling Brand Y..."
Sometimes, all of our agents our busy, so a call gets routed to our overflow team. Our overflow team might take a call for Brand X one minute and then a call for Brand Y the next minute, so it's important that the Caller ID tell them which brand/number/queue was dialed by the customer.