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86 Chapter 4: Configuring Asynchronous Connections with Modems

wait for anything except string = " ". The router then issues the ATZ, or modem reset, command,
using a send string. The router waits for the modem to respond OK, which is the normal modem
response to ATZ. The router then sends the ATDT command and replaces the \T with the phone
number to make the call. Last, the TIMEOUT 30 declares that the call is considered "not
answered" if no carrier is obtained in 30 seconds. Once the connection is made, the chat script
sends a c, which is a carriage return.

Provided that the router, the modem, and the phone number are correct, the physical layer
should now be established! Congratulations! You can now move on to the upper layer
protocols, such as PPP (see Chapter 5, "Configuring PPP and Controlling Network Access")
and advanced uses (see Chapter 6).