Troubleshooting Dual-Channel ISDN Connection Problems

• The Microsoft Network versions 1.2, 1.3, 2.0, 2.5

SUMMARY

This article contains information to help you identify why the second channel on your ISDN adapter may not connect to MSN, The Microsoft Network.

MORE INFORMATION

Your ISDN adapter Can Support Only a Single Channel

Not all ISDN adapters can support more than one channel. Read the documentation included with your adapter to identify whether your ISDN adapter can support Multilink PPP.

Your ISDN Line Is Not Set Up for Dual-Channel Connections

When you have your ISDN line installed, you may need to specify to your ISDN provider that you need two channels provisioned on your line. This is not always the default configuration from your ISDN provider.

Your ISDN Adapter Settings Are Not Correct

With most ISDN adapters that can support Multilink PPP, you must change the settings to enable dual-channel capabilities. Use the documentation included with your adapter to identify which settings to use for Multilink PPP. Then, you can change the settings using these steps:

1. Click Start, point to Settings, and then click Control Panel.

2. Double-click Modems.

3. Click the ISDN adapter you are using, and then click Properties.

4. On the Connection tab, click Advanced.

5. In the Extra Settings box, type the dual-channel settings for your ISDN adapter. You can find these settings in the documentation for your adapter.

The Two ISDN Channels Are Connected to Different Access Boxes

Internet access numbers sometimes have more than one access box to handle a large number of incoming calls at once. Sometimes, when you connect with two channels, the channels get separated into two different access boxes. This situation is called straddling. When straddling occurs, your second channel might not make a connection. And in some cases, your adapter might not make a connection at all. If this happens, you must wait and try your connection again later.

The Phone Numbers for Your Adapter Are Not Configured Correctly

ISDN lines usually come configured with two phone numbers. When you use dual-channel ISDN, your adapter uses only one phone number. The second number might be the reason your second line is not connecting. This problem is especially common with the 3Com Impact adapter running firmware version 2.02. If you think the second phone number might be the problem, try reconfiguring your adapter to use only one of your ISDN numbers.

If you experience difficulties, please contact technical support for the manufacturer of the ISDN device.