Voice Mail Add-on For an Existing PBX (or CO Switch)

Voice-mail can be easily and economically added to an existing PBX or central office (CO) switch.

For the PBX, a PRI port and an SMDI serial port are required. The PRI is required to forward voice calls (with Called ID name and number) to the Asterisk voice mail system. A voice channel is also used to allow a subscriber to enter the system and listen to messages. Multiple T1 circuits may be used for a high-volume configuration.

The SMDI circuit is a bi-directional serial connection. Using this interface, the switch passes a reason code to the voice mail system to indicate why a call is being forwarded--whether the called number is permanently forwarded, whether the called number was busy, or whether the called number was not answered. The voice mail system uses this indication to select the proper greeting.

The voice mail system uses the SMDI interface to tell the switch to operate or reset the stutter dial tone and/or message waiting indicator (the stutter dial tone is used to indicate a new message).

This diagram illustrates the configuration:



The LAN connection allows the voice mail system to send an e-mail notification for each new message. This notification includes the calling name and number, date and time, message duration, and, optionally, an attached audio file (the audio file allows the user to listen to the message at the PC). The LAN connection also allows the system to be maintained and monitored from a remote location.

When the voice mail system receives a forwarded call, it uses the called number to derive the voice mailbox number (this derivation can be site specific). For example, extension 1234 could map to mailbox 1234.

The switch will also be configured with one extension permanently forwarded to the voice mail system, and this number will be for users to enter voice mail. Once in the system, the user can listen to messages, record greeting messages, change passwords, manage directories, and more. When a user enters the voice mail system, the calling number is used to derive the mailbox number. If the calling number is not recognized the user will be prompted for the mailbox number and password.

The voice mail system can also be used to provide conference bridging. For conferencing, the PBX would be configured with a group of extensions permanently forwarded to the voice mail system. The voice mail system would then bridge together all calls to those extensions. Also, this conferencing feature can be password protected. (Depending on usage, additional PRI voice circuits may be required.)

Features

  • Voice mail for every employee (or subscriber)
  • Password protected mailbox
  • Separate busy and unavailable messages
  • Default or custom greetings
  • Multiple mail folders
  • E-mail notification of voice mail message with audio file attachment
  • Voice mail message forwarding
  • Message waiting stutter dial tone and/or message waiting indicator
  • Option to have the Caller-ID of the caller heard before the voice mail message
  • Option to review, re-record, or save voice mails after leaving them
  • Option to review, re-record, or save busy, unavailable, and name prompts