Connection via IP-PBX

Business Issue/Requirement

Increasingly, organizations are deploying IP-PBX phone systems. In many cases, the phones connected to these PBX’s are capable of wideband audio. However, when someone from a PBX station dials a regular PSTN telephone number, such as a teleconferencing access number, the call is typically routed over the PSTN and therefore restricted to a narrowband connection.

PBX users should be able to automatically connect to a conferencing service in wideband with minimal special procedures. This functionality should be established centrally in the PBX, without the need to create provisions for each individual telephone station. It should also be possible for the conferencing service to DIAL OUT to PBX users (even if they do not have PSTN direct-inward-dial numbers), and for those connections to be in wideband.

ZipDX Feature

ZipDX uses advanced technology that allows connections from PBX systems using SIP. The PBX need only be programmed to recognize the ZipDX dial-in number and route the call to the ZipDX conferencing server over a SIP trunk via the Internet. ZipDX will then negotiate directly with the telephone end-point to enable the call in wideband, if possible. ZipDX will automatically recognize the user, provided the PBX sends an identifier as part of the “FROM” address in the SIP header, and the user has included this identifier in their ZipDX profile.

ZipDX can also dial out to conference participants via a SIP identifier, or URI. As long as the PBX makes a URI available to route the call directly to the user’s extension, the user need only include the URI in their ZipDX profile as a “call me” destination.

Use this Feature

Detailed configuration instructions for various PBX models are available in the personal profile section after log in at

This feature may require some testing to get it right. To test calls TO ZipDX, configure your PBX to “trap” calls to 1-888-ZipDX-88, and route those calls to this SIP URI: The PBX should identify the calling station by including a FROM header, such as {station}, where {station} is a numeric or alphanumeric identifier for the extension placing the call (such as On the profile tab at, include that SIP header in the “dial-in numbers” box as “ ”

When you dial ZipDX from your PBX extension, it will now greet you by name automatically. Your call will be in wideband, if supported and enabled by your telephone. You can also test connectivity and routing by directing this demo number to ZipDX the same way: 1-888-947-3987. When you dial that number, a greeting will indicate if your call is in wideband or narrowband.

For calls from ZipDX to your extension, follow the URI example above; include “” in the “Call-me” numbers box in your profile. Make sure you have the call-me feature enabled in your profile. Then, schedule a ZipDX call. Shortly before the designated time, ZipDX will call your extension. The call will be in wideband, if supported and enabled by your telephone.

Notes: For troubleshooting and technical support, please E-mail