You may run into situations where a router in a remote location needs to dial in to a central router, but the toll charges are much higher if the remote router makes the call. This scenario is perfect for PPP Callback, where the callback client places a call to a callback server, authentication takes place, and the server then hangs up on the client! This ensures that the client isn’t charged for the call. The server then calls the client back.

In the following example, R2 has been configured as the client and R1 is the callback server. Let’s look at both configurations and the unique commands PPP Callback requires.
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