How Blueworx Voice Response performs call tromboning

A trombone operation occurs when a call coming in on one Blueworx Voice Response channel connects directly with an outgoing call on another Blueworx Voice Response channel. This is how it works:
  1. A call arrives at Blueworx Voice Response, and the application decides that the user needs to be connected to a third party by using a trombone operation. The application then uses a custom server function to initiate this operation.
  2. The custom server requests Blueworx Voice Response to make an outgoing call to the third party on another channel.
  3. When the third party answers, they are connected to the original caller using the TDM H.100 bus that is internal to the Blueworx Voice Response system.
Note: When using the DTNA software simulation of a DTEA card, call tromboning between DTTA PSTN channels and VoIP/SIP channels is not possible, although it is possible to trombone between DTNA channels.

Using call tromboning

You can use call tromboning:
  1. To simulate transfer. If the telephony protocol you are using cannot support transfer, you can use the trombone operation to simulate a transfer operation. The connection is maintained until either the caller or the third party ends the call by hanging up. The disadvantage of this operation over a normal switch-based transfer operation is that two Blueworx Voice Response channels are occupied for the whole time that the caller and third party are talking. With a switch-based transfer, the channel between the caller and Blueworx Voice Response is broken as soon as the caller is transferred to the third party.
  2. To allow reference to a third party, then returning to the Blueworx Voice Response application. The trombone allows the caller to consult a third party. When the third party hangs up, or the caller ends the consultation, the caller is connected back to Blueworx Voice Response at the point where they left the application they were using. This might be useful in a voice mail application, for example, where a caller can break out to respond to an urgent voice mail message, then return to processing the rest of the voice mail.

For details of how to install, configure and use the trombone custom server, refer to the Blueworx Voice Response for AIX: Designing and Managing State Table Applications information.