This section presents general requirements for modems.
The fundamental design principle for compatibility with Windows NT is for the device to be supported by the Universal Modem Driver (Unimodem), which uses INF files to characterize the behavior of a device. The detailed definition of Unimodem requirements is contained in the MDK available from ftp://ftp.microsoft.com/developr/drg/modem/modemdev.exe.
Note: It is recognized that OEMs supply systems to corporations in situations where the customer will insert modem devices at the end-user site or where the customer has particular feature demands. Server systems designed for specific corporate customers are exempt from these requirements.
66 System includes modem communications device
The following device options, as defined later in this chapter, can meet this requirement:
Modem with 33.6 Kbps or better capabilities, supporting server fax capabilities.
Recommended: Two or more ports.
ISDN adapter.
ATM adapter.
67 Modem supports TIA-602, Hayes-compatible command set
TIA-602 codifies the most common data modem. As part of the command set, the modem must have a distinct means for controlling the reporting of modem-to-modem protocols, so the modem can be forced to generate recognizable reports for modulation, error control, and data compression. Examples include the Wn command, the S95 register, the \Vn command, and the ITU V.25ter +MR, +ER, and +DR commands.
Recommended: ITU V.25ter, which is a superset of TIA‑602, with significant and useful improvements. It includes three new components:
A standard format for extending the AT command set, with standard means for the system to test the range of supported values for each command. This format enables adaptive modem installation.
Standard extensions for modem ID, port control, modulation control and reporting, error control, and data compression control and reporting. Use of these extensions reduces or eliminates the need for data modem INF files.
Standard commands in Annex A (1996) in order for the system to use V.25, V.8, and V.8bis call-control features. These commands enable point-to-point data calls and voice/data/video calls.
The particular utility of the standard format is that it allows a future modem installer to adaptively install and use a modem with minimal need for INF minidrivers. This standard format will be provided in versions of the MDK, available in the second half of 1997 through MSDN Professional membership.
68 Data modem supports 33.6 Kbps (V.34–1996) with V.42 and V.42bis protocol
This is the minimum modem capability specified in this guide.
69 Data modem supporting speeds over 33.6 Kbps can be upgraded to V.pcm
Any modem that supports a speed faster than 33.6 Kbps must be capable of being upgraded to V.pcm.
See the related requirement, “PCM modem supports ITU‑T V.pcm,” later in this chapter.
70 Fax modem supports 14.4 Kbps (V.17) with Class 1 (TIA‑578‑A) command set
The following are recommended:
Class 1.0 (ITU T.31) with +FAR support, which allows the hardware to perform adaptive carrier detection
Class 2.0 (ITU T.32 or TIA‑592) for server modems
Adaptive DATA/FAX call classification based on the Class 2.0 +FAA command or equivalent, particularly for server modems
Windows NT 5.0 and future versions of Microsoft BackOffice® products will support Class 1.0 and Class 2.0 fax modems and use adaptive call-classification support. To benefit from this support, modem vendors should extend their modem INFs to support the new registry keys needed to support these features, as defined in the MDK available in the last quarter of 1997.
71 Data modem supports V.80 for synchronous access
This standard provides a control plane for the modem and synchronous access to the data path, the foundation for third-party voice/data/video software (for example, H.324, V.70). Modems that support V.80 should also include V.8bis signaling and V.25ter Annex A as described in the following item.
72 Modem supports adaptive connection, V.25, V.8, and V.8bis call control signaling with V.25ter Annex A modem commands
V.25 defines basic call-type selection, with an answer tone, a fax-calling tone, and a data-calling tone. V.8 defines advanced call-type selection, with complex information exchanged between terminals; V.8 is used in V.34, V.pcm, and some digital simultaneous voice/data (DSVD) implementations. V.8bis is required for standard multimedia modes: V.61 ASVD, V.70 DSVD, and H.324 video telephony.
V.25ter Annex A enables the computer to participate in call control, allowing flexibility and a visual user interface, as well as saving modem complexity.
73 Modem supports blacklisted and delayed number clearing
The modem should clear its blacklisted and delayed number tables if the associated handset goes off hook.
During certain international PTT (Post, Telephone, and Telegraph) certification processes, modems must support the blacklisted and delayed numbers feature. That means that when the modem fails to connect to a specific number for a certain number of times, the dialed number is stored in an internal list. Any subsequent automated dialing operation to this number is then either delayed for a time (delayed) or might be forbidden until some form of manual intervention occurs (blacklisted). The international certification processes specify that manual intervention using an external device is required in order to clear these numbers.
74 Modem supports TDD, meeting V.18-1996 with V.25ter AT commands
People with deafness or reduced hearing can use Telephone Device for the Deaf (TDD), also known as Text Telephones, to communicate over phone lines. The U.S. Americans with Disabilities Act (ADA) requires all businesses of a certain size or larger to have Text Telephone services available and to be able to receive calls from people using Text Telephones.
In North America and Europe, the following types of Text Telephones are used:
Baudot: 45 or 50 bps Frequency-Shift-Keyed (FSK) and 5‑bit Baudot coding
ASCII: 300 bps Bell 103 and 7‑bit ASCII coding
European Deaf Telephone (EDT): 110 bps half-duplex V.21 and 7‑bit coding
Minitel: V.23 modems and 7‑bit coding
Modems and 7‑bit coding
DTMF: 2‑digit or 3‑digit character coding
The International Telecommunications Union (ITU) recommendation V.18 codifies how all these devices work and how to adaptively connect to all of them. ITU recommendation V.25ter contains AT commands for control of V.18 features in a modem.
It is recommended to include Text Telephone capability for the type commonly used in the country of sale and use (for example, Baudot in the United States, Minitel in France, and so on).
75 PCM modem supports ITU‑T V.pcm
For PCM modems (faster than V.34‑1996), ITU V.pcm is a requirement. Compliance testing for this requirement will begin within a reasonable time frame after ITU V.pcm is approved by ITU Study Group 16 (currently projected for January 1998). If V.pcm has not been approved by the time compliance testing begins for these guidelines, the modem must be end-user upgradable through software to the current version of V.pcm. It is critical not to strand end users with devices that must be replaced later.
76 Modem controller meets minimum requirements
The following are minimum requirements for the modem controller:
Unimodem Diagnostics command, AT#UD
Software-upgradable modem controller (that is, upgradable ROM or Windows modem)
AT command buffer of at least 60 characters
Semicolon (;) character dial string modifier
Connection reporting: DCE rate; Error Control and Data Compression
The following are recommendations for the modem controller:
V.25ter +GMI and +GMM commands for modem identification. This is useful if the modem is installed with a CID.
V.25ter +I, +M, +E, and +D commands. This allows automated generation of data modem INF registry entries.
77 Voice modem supports TIA‑695 (AT+V)
TIA IS‑101‑1994, the Interim Standard for Voice DCE, has been superseded by TIA‑695. TIA‑695 adds voice formats and speakerphone control commands. ITU‑T plans an equivalent recommendation (V.voice) to be completed and assigned a number in January 1998. V.voice will add some small corrections to TIA‑695, plus provisions for duplex voice.
Voice capability is not mandatory, but if support for voice modem is implemented in a server system, it must meet the following requirements:
Voice recording and playback
DTMF generation and detection during voice I/O
Voice I/O support of 8‑bit, 8‑kHz PCM formats: unsigned linear, G.711
Programmable gain control for all audio channels
Speakerphone with automatic training (no user intervention)
Voice I/O to the handset (for voice-only devices)
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