Cisco Systems DC-145 manual DC-150, EXEC Creation on a Line Configured for Modem Dial-In

Configuring and Managing External Modems

Supporting Dial-In Modems

Figure 24 EXEC Creation on a Line Configured for Modem Dial-In

Idle state

DTR low, watching

CTS

Ring transition

Raise DTR

Lower DTR

Answer timeout

Hang up DTR low

Lower DTR

close connection

CTS lowered

or exit

DTR high

Ready and active

DTR high,	Ringing
watching
CTS

CTS raised

Create EXEC

S1001a

Note The modem callin and modem cts-requiredline configuration commands are useful for SLIP operation. These commands ensure that when the line is hung up or the CTS signal drops, the line reverts from Serial Line Internet Protocol (SLIP) mode to normal interactive mode. These commands do not work if you put the line in network mode permanently.

Although you can use the modem callin line configuration command with newer modems, the modem dialin line configuration command described in this section is more appropriate. The modem dialin command frees up CTS input for hardware flow control. Modern modems do not require the assertion of DTR to answer a phone line (that is, to take the line off-hook).

Cisco IOS Dial Technologies Configuration Guide

DC-150