User Manual

Modems Ports
5-10
5.2.7 Modem Configuration Checklist
These items should be verified after any modem configuration. Note that some options might not be
provided on the modem in question.
◆ The modem must disconnect immediately when DTR is dropped.
◆ The modem must assert CD (or DSR, if connected) when connected to another modem and must not
assert CD when disconnected. The modem may optionally assert CD during outbound dialing.
◆ The modem and ETS must agree on the flow control method and baud rate scheme.
◆ The modem must not send result codes or messages to the ETS except optionally during outgoing
calls.
◆ Configuration information should be saved in non-volatile memory (NVRAM) so that it will be
retained during power outages.
◆ The modem should restore its configuration from non-volatile memory when DTR is dropped.
◆ The modem should be configured to answer the phone if incoming connections are to be supported.
Generally this is done with the ats0=1 command.
◆ The modem should not answer the phone unless DTR is asserted by the ETS.
These items should also be verified after any ETS port configuration:
◆ Modem Control must be enabled. Using modems on ports without Modem Control enabled will lead
to security problems. See the Define Port Modem Control command on page 12-43 for syntax and
details
◆ Baud, parity, and flow control settings should be verified with the modem setup.
◆ Autobaud should only be enabled if required.
5.2.8 Testing the Modem Configuration
The example tests in this section assume that the modem is attached to port 4 and the modem and ETS
checklists have been followed.
Dial into the ETS and issue the Test Port command. A regular cascading pattern should be printed. If
characters are lost after a few dozen lines, there is a flow control problem.
On another port, issue the Logout Port 4 command. The modem should immediately hang up and be ready
for the next call in a few seconds. If not, the modem is ignoring DTR, or there is a wiring problem. Repeat
this procedure with all expected modem speeds and options.
Dial into the ETS, connect to a network host, and log in. Hang up the remote modem without logging out
of the ETS. After the ETS’s modem hangs up, issue the Show Port 4 command from another port. The port
should be in the Idle state.