3.3 PPP Callback
3.3.5 Configuring a callback client
You can set up a Cisco router to initiate a PPP callback request. As shown in the Figure, configure client PPP callback so that all calls over this interface request callback (the following step numbers correspond to the numbers in the Figure):
  1. Configure PPP on the serial or ISDN interface.
  2. Set up a dialer map with the dialer map and dialer-group commands. Be sure that the dialer map command has a name field with the correct name of the server; in the Figure, the name is Plano.
  3. Configure the router interface as the callback client with the ppp callback request command.
  4. Set the authentication to CHAP with the ppp authentication command.

Note that you can use the optional dialer hold-queue timeout command to specify the number of seconds that the callback client waits for a return call from the callback server.