Using call progress tone detection for outbound calls

This section outlines how call progress tones are used for outbound dialing. For specific information about using call progress tones in a state table, see the Dial, MakeCall, TransferCall, and ReconnectCall actions in the Blueworx Voice Response for AIX: Application Development using State Tables information.

A telephone call from one person to another typically proceeds as follows:

1. First, the caller takes the handset off the hook and listens for a dial tone.
2. Having confirmed the presence of dial tone, the caller proceeds to dial.
3. The caller then listens for an audible ring tone.
4. When the called party answers, the caller detects a voice and knows that the call has been answered. The call setup is now complete.

   Of course, other possible results can occur during call setup, such as hearing a busy tone instead of an audible ring. A caller would hang up and try again later.

Blueworx Voice Response makes outbound calls in much the same way.

The application developer can program the state table to control the decisions during call setup:

1. When a Dial, MakeCall, ReconnectCall, or TransferCall action goes off-hook, the call progress tone function is activated to search for a dial tone. If a dial tone is not detected, several possibilities exist, including hangup. For more information, see the Dial, MakeCall, TransferCall, and ReconnectCall actions in the Blueworx Voice Response for AIX: Application Development using State Tables information.
2. If a dial tone is detected, dialing follows.
3. After the number is dialed, the call progress tone function is activated again to search for an audible ring tone.
4. Several possible results can be returned by the call progress tone function:
   • If the destination phone rings, a positive audible ring result is returned.
   • If the phone is engaged, a busy (line) result is returned.
   • If the phone is answered, a voice energy presence result is returned.

In summary, Blueworx Voice Response detects a specific type of tone at each step during call setup. The returned value indicates the result of the tone search, which in turn indicates the status of a call.

A Blueworx Voice Response application can receive an unexpected tone; that is, a tone that should not occur at a particular point in the dialing sequence. For example, a dial tone should not occur after a ring tone. If such an unexpected tone is received, Blueworx Voice Response then returns the Tone Identifier and the Tone Type to the application (see How call progress tones are identified).

The application can then perform some action, related to the unexpected tone it receives.