Digicom 3910, 3911 operation manual Branch

Troubleshooting

	Table B-5
	(2 of 2)
	Modem — VF Connection
Symptom	Action
The modem does not go off-hook	If using AT Dialing, refer to Table B-4, Modem— DTE Connection.
and begin dialing.	If using DTR Dialing, verify the telephone number stored in directory
	location 1, and verify that the DTE is raising DTR from Off to ON to
	initiate a dial.
	If using V.25bis Async, verify that the correct character format is set to
	7 data bits with even parity and 1 stop bit, and the carriage return and
	line feed are used as command terminators.
	If using V.25bis Bisync, verify that the correct character format uses
	two synchronous control characters and a start-of-text control
	character before the text block, and an end-of-text control character
	after the text block.
	If using V.25bis HDLC, verify that the character format uses flag,
	address, and control characters before the text block and a frame
	sequence check and flag after the text block.
The modem dials but does not	If the modem is operating behind a PBX, determine if a 9 and comma
connect.	are needed before the telephone number.
	Verify whether Tone or Pulse dialing is needed.
	Verify that both modems are configured the same in regard to Error
	Control. Try calling in Buffer mode.
	If both modems use V.32bis or V.32 modulation, try setting the
	modem’s V.32bis Train configuration option to Long.
Intermittent disconnects, high	Perform an End-to-End test. Refer to Pattern in Chapter 8, Test
error rates, or excessive	Branch.
retransmissions occur.
The modem establishes and	You may have a poor VF connection. Try dialing again.
then disconnects the call.	The remote modem may have encountered an error control (EC)
	disconnect. If the modems cannot negotiate EC, then a disconnect
	occurs.
	The remote modem may be in a forced Error Control mode (disconnect
	if there is no error control). Reconfigure your modem to V.42/MNP or
	Buffer and try again.
	Check the LCD to determine the reason for the disconnect.
	Perform a Local Analog Loopback test.
High error rates occur when	Incoming rings can cause data errors during a loopback test. Abort the
running a local loopback or	test, disconnect the modular VF cord, and restart the test.
self-test.

3910-A2-GN32-40 September 1998 B-5