User manual
Table Of Contents
- Table of Contents
- About This Guide
- Introduction
- ISDN LAN Modem Functionality Description
- Hardware Description and Installation
- Setting Up TCP/IP for Windows and Macintosh
- Configuring the ISDN LAN Modem
- Advanced Configuration
- Before you Begin
- Setting Up Additional Service Providers
- Editing Service Provider Profiles
- Restricting Workstations from Accessing Service Provider(s)
- Configuring Your LAN Parameters
- Changing Data Call Parameters
- Changing Voice Call Routing
- Reserving DHCP Addresses
- Selective Password Protection
- Changing Your Password
- Setting Up Your ISDN Line Manually
- Locking and Unlocking the Configuration
- Configuring the ISDN LAN Modem from a Remote Location
- Supplementary Voice Call Services
- Placing, Receiving and Disconnecting Calls
- Troubleshooting and Maintenance
- Networking Primer
- What is a network?
- What is a LAN?
- What is a WAN?
- How does a LAN connect to a WAN?
- What is a LAN modem?
- What is ISDN?
- How do different devices communicate with each other?
- What is TCP/IP?
- What is an IP Address?
- What is a Subnet Mask?
- Dynamic and Static IP Addresses
- What is DHCP?
- What is DNS?
- What is NAT?
- What are numbered and unnumbered links?
- How is overall throughput determined?
- What is a network?
- Using the Custom Web Browser
- ISDN LAN Modem Factory Defaults
- ISDN LAN Modem Specifications
- Ordering ISDN Service
- If You Place Your ISDN Order Through 3Com
- If You Place Your ISDN Order Through the Telephone Company
- Supplementary Voice Features Included with U, EZ-ISDN-1, V and EZ-ISDN 1A
- Limitations of ISDN Ordering Codes U, EZ-ISDN 1, V and EZ-ISDN 1A
- What If I Already Have ISDN Service?
- Table of ISDN Ordering Code Capabilities
- Glossary
- Index
- 3Com Corporation Limited Warranty

98 C
HAPTER
9: T
ROUBLESHOOTING
AND
M
AINTENANCE
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.
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.
Cannot receive an incoming
call.
Bandwidth Allocation may be set
to Use two B Channels.
Two separate data calls are up.
Your ISDN line does not support
simultaneous voice and data on
both 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.
Your ISDN line does not have
ACO.
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,
or drop voice calls.
Flexible calling is not enabled. From the ISDN LAN Modem’s main configuration page,
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
older codes for these services.
From the ISDN LAN Modem’s main configuration page,
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
signal even when line is busy.
Message service is enabled on the
ISDN LAN modem but you do not
subscribe to voice mail from the
telephone company.
From the ISDN LAN Modem’s main configuration page,
click ISDN Parameters. Under Message Service Enable,
make sure both boxes are clear.
(continued)
Table 6
Symptoms, Causes, and Solutions
Symptom Possible Cause Solution