SMDI via RS-232

Manufacturer: Any SMDI interface

Model: SMDI interface via RS-232 cable

Software Version: Centrex specification

Hardware Requirements: Centrex or any phone system using the standard SMDI integration. RS-232 cable between telephone company provided modem and the VoiceTrak system. Special VoiceTrak software is required.

VoiceTrak Parameter Settings:

Global Lc Off -1
Custom Page 1 Extension Length (see notes) 4
Custom Page 2 Message Light On E
Custom Page 2 Message Light Off E
Custom Page 2 Fixed/Var Box 1

Environment Setup

VOICE.BAT file must include SET PBXTYPE=1AESS

VOICE.BAT file must include SET CENTREXPREFIX=xxx (see notes)

Optional Busy Forward message requires the line SET DTMFBUSY=B

Important: All other VoiceTrak parameters must be set to Default.

Use Tone/Cadence file: Accucall should be run for all SMDI integrations.

Important: All other VoiceTrak parameters must be set to Default.

Operational Overview

SMDI is a standard voice mail integration used by telephone company central office switches, some PBX manufacturers and interface devices like VoiceBridge. VoiceTrak connects to standard telephone circuits (often called 1FB's) or single line circuits from telephone equipment. An additional connection exists between an RS-232 (COM) port on VoiceTrak and another RS-232 circuit from the telephone company, the on-site telephone equipment or a unit like VoiceBridge. This additional circuit provides the data necessary for the advanced integration. VoiceTrak conforms to the published specs for SMDI.


The VoiceBridge family of products includes VoiceBridge-II, VoiceBridge-III and VoiceBridge-PC. These products create an easy to use "bridge" between existing or new PBXs and state-of-the-art communications applications.

Voice Technologies Group, Inc.,


Transfer to fax machine. The tone table includes incoming fax detection. You may add an "X" type mailbox which transfers to a fax machine. Also add a line to the VOICE.BAT file which says: 'SET FAX_BOX=xxx' where xxx is mailbox for the fax machine. Not all fax machines send good CNG tones and will not transfer, but if fax tones are detected, the call will transfer to the extension specified in the FAX_BOX setting.

Disconnect Signal

Most Central Office facilities provide a loop current drop upon termination of the connection. This is the best possible approach and allows VoiceTrak to disconnect immediately. It is not necessary to use the VoiceTrak 'grunt' feature.

PBX Ports

A new file must be created in the C:\C2C directory. This file allows modification of the message desk terminal.

The numbers vary based on the connected equipment. On some systems - like VoiceBridge - these numbers may begin with 0001 through the highest VoiceTrak port, typically 0004, 0008, 0012, etc. Documentation indicates these can range from 0001 to 2047. These are NOT the physical phone system ports if doing an SMDI integration via NewBridge. These probably start with 1 (like the example).

You must know the port numbers which will be sent by the equipment (CO, VoiceBridge, or PBX) to set this variable!

For a 4 port system, the text file PBXPORTS.DAT would include only 4 lines and would appear exactly as:


This file must be added to the C:\C2C directory.

VoiceTrak Programming

The VOICE.BAT file must include the following set commands:

set CENTREXPREFIX=xxx ' See notes!
' The next several lines set the data communications link
set comport = x  ' where x is the RS-232 port to use on VoiceTrak (1 or 2)
set baudrate=y  ' where y is the baudrate (suggested 1200)
set parity=0  ' Must match the modem (0=none, 1=odd, 2=even)
set databits=8  ' Must match the modem (5, 6, 7 or 8)
set stopbits=1  ' Must match the modem (1 or 2)
' set datadelay=0  ' See special note below
set DTMFBUSY=B ' See note on Busy Forward options

Note on datadelay: This parameter sets the time to wait between the transmission of each character in the transmit buffer, in tenths of a second. If datadelay is set to 1, there will be a tenth of a second delay between each character sent (for MWL information). It was not necessary to set this parameter at our beta sight and we recommend that this line not be added to the voice.bat file.


Your installation will typically use 4 digit extension numbers with a common prefix (456, 397, etc). You must tell VoiceTrak what prefix digits to expect through the interface. Also note that it is possible to define 3 digit mailbox numbers with a 4 digit prefix, or even 5 digit mailbox numbers with a 2 digit prefix. HOWEVER: All mailbox numbers must be the same length, and the combination of mailbox number and prefix must equal 7. It is imperative that the Extension Length setting in VoiceTrak be set correctly for the mailbox length which will be used.

IF USING VOICEBRIDGE unit read this!

The VoiceBridge unit and other integrations require the station number be padded with zeros. Station 456 must appear as 0000456. To accomplish this padding, add the proper number of zeros to the CENTREXPREFIX variable. Example:

3 digit boxes, use: SET CENTREXPREFIX=0000
4 digit boxes, use: SET CENTREXPREFIX=000

The extension length and the number of digits in CENTREXPREFIX must equal 7. If this is not set properly the message waiting lights won't work properly.

Message Waiting Indicators

The message waiting indicator on Central Office equipment consists of a stutter tone. The stutter tone will be heard when the desk set goes off hook. The stutter tone will terminate when the mailbox holder calls in to retrieve messages.

Systems connected via VoiceBridge will use the message indicators of that phone system.

To forward the phone to voice mail

Follow the instructions from the telephone company or the VoiceBridge instructions for your phone equipment.

Busy Forward.

Callers forwarded to VoiceTrak when the desk set is busy can be handled one of two ways. Option I plays the active personal greeting of the called party for the caller, and the caller is prompted to leave a message. Option II informs the caller that the called number is busy and allows the caller to remain on hold or leave a message. If the caller chooses to remain on hold the system will automatically ring the extension again in about 30 seconds. Note that Option I or Option II are system wide features. To set Option II and inform callers when an extension is busy, add the following line to the VOICE.BAT file after the PBXTYPE line: SET DTMFBUSY=B


The desk set should be programmed for Busy/No Answer Forward to VoiceTrak at all times. If the system user wants all calls forwarded to VoiceTrak, the All Call Forward feature should be programmed.

No Answer Forward. The caller will hear ringback, then a hookflash, then the personal greeting of the called party. The caller may touch 3 to skip the greeting and instructions or remain on the line and wait for the 'gong' tone to leave a message.

All Call Forward. The caller will be transferred immediately to the personal greeting of the called party and has the same options listed for No Answer Forward.

Busy Forward. Option I: This produces the same result as All Call Forward. Option II: The caller will be informed the extension is busy and will be given options to remain on hold, leave a message or disconnect. If the caller elects to hold the length of the hold will be determined by the length of the recordings MESS500.VOX to MESS507.VOX. These recordings are currently about 30 seconds but recordings of a different length may be substituted by the system administrator if desired.

Message Waiting Indication. A message waiting indication is provided through a stutter tone. When the handset is lifted the sound heard will be a stutter tone instead of a steady dial tone. A normal dial tone indicates that no new messages have been left. The last VoiceTrak port must be free for VoiceTrak to activate or deactivate message waiting indicators.

Direct Calls to Retrieve Messages. When the designated extension is used to call VoiceTrak, the CO sends a signal to VoiceTrak indicating that a direct call has been initiated. This eliminates the need for the user to dial "*" plus the 7 digit extension number. Depending upon whether or not a password has been activated, the system user will hear, "Please enter your password" OR "You have __ new messages, __ old messages". Note that when the system user calls from a phone outside the office it will be necessary to call the 7 digit VoiceTrak number, then touch "*", then dial their personal 7 digit number, then dial the a password, if established.

How does it work?

Immediately prior to ringing a VoiceTrak port, the CO sends a data stream indicating the port number to receive the call and a description of the call. The description includes the mailbox number and information like forwarded on busy, direct call to check for messages or no answer/all call forwarded. VoiceTrak handles the call according to the call description it receives. Also note that message indication occurs in the background without occupying a port. The normal VoiceTrak debug window shows all incoming and outgoing data to the CO. The last 100 debug lines can be captured in the file LIST.LST by pressing F4, and can be reviewed off-line.

Integration verified using several systems, including a VoiceBridge unit connected to a Northern Telecom SL1. The VoiceBridge unit supports the SMDI standard and this integration can be used with SMDI or any device supporting the SMDI protocol.

VoiceTrak is also being used with SMDI integration directly connected to CO lines and an RS-232 circuit to the CO.