3Com 3C892 manual Enabled on your Isdn line

98CHAPTER 9: TROUBLESHOOTING AND MAINTENANCE

Table 6 Symptoms, Causes, and Solutions

Symptom Possible Cause Solution

Cannot receive an incoming call.

Attempted to place a voice call over a directory number that is already in use for a data call. If this is the case, your ISDN line is configured to allow only one B channel per directory number.

Bandwidth Allocation may be set to Use two B Channels.

Contact you telephone company if you want to have simultaneous voice and data on both B channels.

For a Lucent 5ESS switch, your ISDN line must have Max B Channel Limit=2 for simultaneous voice and data.

For a Siemens switch, your ISDN line must have Number of B Channels Per Call Type Per Office Equipment Directory Number (NBCCTOEDN) =2.

Two separate data calls are up. Your ISDN line does not support simultaneous voice and data on both B channels.

Your ISDN line does not have ACO.

Contact you telephone company if you want to have simultaneous voice and data on both B channels.

For a Lucent 5ESS switch, your ISDN line must have Max B Channel Limit=2 for simultaneous voice and data.

For a Siemens switch, your ISDN line must have Number of B Channels Per Call Type Per Office Equipment Directory Number (NBCCTOEDN) =2.

Contact you telephone company to have ACO added.

The analog modem connected to the ISDN LAN Modem is unable to detect dial tone when attempting to place an analog call while a Multilink PPP call is established.

The standard period of time most modems are set to wait for a dial tone before hanging up the call is 2 seconds, which is about the same amount of time it takes the ISDN Modem to drop the second B channel from a Multilink PPP call and re-establish a dial tone.

Adjust the analog modem setting as follows: Change S-Register 6 (Wait Time for Blind Dialing) on the analog modem to a value of 3 or higher (the default is usually

2)to increase the period of time your analog modem is set to wait before hanging up the call.

Cannot conference, transfer,	Flexible calling is not enabled.	From the ISDN LAN Modem’s main configuration page,
or drop voice calls.		click ISDN Parameters. Under Flexible Calling Enabled,
		check the telephone number check box for which you
		want Flexible Calling enabled.
		If Flexible Calling is enabled on the ISDN LAN Modem,
		check with your telephone company to make sure it is
		enabled on your ISDN line.
	Your telephone company uses	From the ISDN LAN Modem’s main configuration page,
	older codes for these services.	click ISDN Parameters. Under Supplementary Services,
		enter the following in the Codes field: 6 for
		Conference, 7 for Transfer, 8 for Drop and 9 for
		Message Service.
Caller always hears a ringing	Message service is enabled on the	From the ISDN LAN Modem’s main configuration page,
signal even when line is busy.	ISDN LAN modem but you do not	click ISDN Parameters. Under Message Service Enable,
	subscribe to voice mail from the	make sure both boxes are clear.
	telephone company.
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