Paradyne 3800PLUS manual 2 of, Modem ± VF Connection, Symptom, Action, Table C-3, Branch

Troubleshooting

	Table C-3
	(2 of 2)
	Modem ± VF Connection
Symptom	Action
Modem goes off-hook, answers, but does	Perform a Local Analog Loopback test and verify that data entered at the DTE
not connect	is echoed back to the DTE.
	Verify that the originating modem is compatible.
	Verify that originating modem recognizes your modem's answer tone.
	Verify that originating modem supports your modem's modulation schemes.
	The 3800Plus modem recognizes CCITT V.34, V.32terbo, V.32bis, V.32,
	V.22bis, V.22, V.21, Bell 212A, and Bell 103J. It does not support other
	vendors' proprietary modulation schemes.
	Force your modem to operate at the same modulation scheme as the
	originating modem to see if they connect.
Originate Mode	Verify that the modem's DTE Dialer configuration option is set to the correct
	setting: either AT, DTR Dialing, V.25bis Async, V.25bis Bisync, or V.25bis
	HDLC.
Modem does not go off-hook and begin	If using AT Dialing, refer to Table C-2, Modem ± DTE Connection.
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 correct character format uses flag,
	address, and control characters before the text block and a frame sequence
	check and flag after the text block.
Modem dials but does not connect	If the modem is operating behind a PBX, verify if a 9 and comma are needed
	before the telephone number.
	Verify whether Tone or Pulse dialing is needed.
	Verify if one modem is configured for Error Control or Disconnect and the
	other modem is configured for no Error Control. Try calling in Buffer mode.
	If both modems use V.32bis or V.32 modulation, set the modem's V.32bis
	Train configuration option to Long.
Intermittent disconnects, high error rates,	Perform an End-to-End test. Refer to Pattern located in Chapter 7, Test
or excessive retransmissions	Branch.
Modem establishes and disconnects a	You may have a poor VF connection. Disconnect and dial again.
call	The remote modem may have encountered an EC Disconnect, where the
	modem is configured to establish a call using error correction. 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 verify the reason for disconnect.
	Perform a Local Analog Loopback test.
High error rates occur when running a	Incoming rings can cause data errors during a loopback test. Abort the test,
local loopback or self-test	disconnect the modular VF cord, and restart the test.

3980-A2-GB30-20 November 1996 C-3