ISDN Requirements

This section summarizes the design features for ISDN devices.

In this section, “internal ISDN device” refers to the ISDN terminal adapter, which exposes raw access to its B channels using NDIS miniports. NDIS miniports could also be attached to the PC using WDM-supported bus classes such as USB (thereby physically being an external device).

In this section, “ISDN modem” refers to an internal or external ISDN device that exposes itself as a modem controlled by the AT command set. Certain ISDN devices might be attached to the PC internally or externally, exposing serial ports or modems to the system. To Windows operating systems, these devices look like modems, and the operating system can use these devices as modems, provided that the hardware manufacturer has done the work to ensure that these devices look and act like modems. This work includes the following:

Interpretation of the standard modem AT command set. This can be done either in the ISDN device itself or in a serial port driver. For more information, please refer to the TIA-602 specification, a subset of ITU V.25ter.
A modem INF file for installing the device and for telling Unimodem which commands to use to control the ISDN device.

This section defines general requirements for ISDN and specific requirements for ISDN terminal adapters. For more information about the requirements for ISDN modems, see the “Modems” chapter in Part 4 of this guide.

For PC 98, ISDN is recommended but not required for high-speed connections. If implemented in a PC 98 system, ISDN must meet the requirements defined in this chapter. For Plug and Play, power management, and driver support requirements, see the “PC 98 Design for Network Communications” section later in this chapter.

16. Internal ISDN device meets PC 98 network adapter requirements

Required

For PC 98, the driver must support NDIS 5.0. Only NDIS 5.0 miniport drivers and INF files are allowed for complete user-friendly installation and operation of the ISDN adapter.

The following requirements must be met, as defined in the “System Requirements for Network Communications” section earlier in this chapter:

Support NDIS 5.0 using a miniport driver
Automatically sense whether a cable is connected
Support quadword buffer alignment or better
Communicate with a driver across any bridge
17. Internal ISDN device supports synchronous HDLC framing

Required

High-level data link control (HDLC) framing is a standard for sending synchronous data. Other framing methods are allowed if the miniport driver provides simple HDLC framed synchronous PPP packets to NDISWAN using NDIS.

18. Internal ISDN device uses NDIS WAN miniport driver

Required

The device must have an NDIS WAN miniport driver to support Windows remote access over ISDN. For information about NDIS status codes and indication mechanisms, see the Windows NT 5.0 DDK.

19. Internal ISDN device includes connection for analog phone

Recommended

Note: This recommendation applies only in the United States.

Adding an analog (POTS) port to the ISDN device delivers convenience to the small-office/home-office (SOHO) market, allowing customers to use one ISDN line to meet all their telecommuting needs at minimal cost. Many customers in this market don’t want a separate analog phone line for their fax machines, modems, or phone when ISDN can do this with a device that has POTS support.

20. ISDN device supports auto-SPID detection algorithms and standard SPID format

Required

Note: This requirement applies only in the United States.

ISDN drivers must support auto-SPID detection algorithms as defined by NIUF in 1997 Version of National ISDN Basic Rate Interface Terminal Equipment Generic Guidelines. This capability eliminates the need for the end user to enter the SPIDs.

ISDN drivers also must support the standard SPID format, which is useful when auto-SPID is not available.

21. ISDN driver supports switch detection

Recommended

The driver can attempt to determine the switch type based on the directory number, or it can use other proprietary solutions to determine the switch type. This enhances the Plug and Play experience for users.

22. ISDN driver supports unattended installation, with limitations

Required

ISDN devices must be capable of being installed without user intervention. The exception is specific ISDN parameters, which must be acquired from the equipment being connected to. Dependent parameters include SPIDs and switch-type IDs.

Notice that it is a PC 98 requirement for the device to support auto-SPID detection algorithms. If these algorithms are also supported on the equipment being connected to, only the switch type should have to be entered during installation of ISDN hardware if it cannot be detected automatically.

23. ISDN device includes built-in NT-1

Recommended

Note: This recommendation applies only in the United States.

NT-1 (network terminator) splits the duplexed transmit and receive signals from the ISDN line into separate transmit and receive components. An ISDN device with a built-in NT-1 can connect directly to the ISDN line. However, doing so prevents other devices from being attached to the ISDN line (only one NT-1 can be connected to an ISDN line).