3.3 PPP Callback
3.3.3 Configuring Async callback
Begin the configuration of PPP callback with the following async callback global configuration mode commands:

Router(config)#username username password password
[callback-dialstring telephone-number]
[callback-line line-number]
[callback-rotary rotary-group-number]

If you configure callback-dialstring “ ”, your router accepts the callback phone number from the caller.

Continue the callback configuration by using the async callback commands in the line configuration or async interface mode, as follows :

Router(config-if)#ppp callback accept
Router(config-if)#ppp callback initiate
Router(config)#line line-number
Router(config-line)#
callback forced-wait seconds
Router(config-line)#
script callback script-name

Lab Activity    
  The Atlanta Bread Company is reviewing the costs incurred by the Macon office for dialin access to the core router. A lower telephone rate has been established for your Atlanta office to call to the Macon office. You will configure callback services between the Atlanta core router and the Macon remote office.