Using ISDN lines

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Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1, Windows Server 2003 with SP2

Using ISDN lines

To enhance connection speeds, you can use an Integrated Services Digital Network (ISDN) line. Whereas standard phone lines typically transmit from 28.8 to 56 kilobits per second (Kbps), typical ISDN devices are capable of 64 or 128 Kbps. This is slower than local area networks supported by high-speed data communications technology, but faster than analog telephone lines. ISDN provides end-to-end digital connectivity between your computer and a remote computer or network by using a local telephone line for network connection.

An ISDN line must be installed by the phone company at your site and at the remote access server. Also, an ISDN adapter must be installed in place of a modem in both your computer and the remote access server. For information about installing an ISDN adapter, see Install an ISDN adapter. Costs for ISDN equipment and lines may be higher than standard modems and phone lines. However, the speed of communication reduces the duration of the connection time, thereby possibly saving toll charges.

An ISDN line comes with two B channels that transmit data at 64 Kbps, and one D channel for signaling that transmits data at 16 Kbps. You can configure each B channel to operate as a port. With this configuration, line speed increases to 128 Kbps. Channel aggregation schemes are specific to each driver, so you must use the same driver and equipment on the client and server.

Multilink dialing over ISDN combines multiple physical links into a logical bundle. This aggregate link increases your bandwidth. To use Multilink, both your connection and the remote access server must have Multilink enabled. For more information about the Multilink feature, see Configuring multiple device dialing.

For information about creating an ISDN network connection, see Make a dial-up connection by using an ISDN line. For information about configuring ISDN network connection settings, see Configure ISDN settings.