How about using an Auto Attendant to play your greeting, redirect to a Call Queue below on a single number.
“Position in queue” will announce the caller’s position in the queue.
“Hold time to agent” will notify the agent of the time that the caller has been in the call queue for.
“Active call queue beep” enables the agent on a call to be notified that there is a call in the queue. ONLY when this setting is enabled the agent can then transfer current calls, between agents, and accept a new call in the queue.