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Practical VoIP Using VOCAL by Luan Dang, Cullen Jennings, David Kelly

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Set Features

Set features are features that depend on the User Agent appliance. The VOCAL system supports Call Transfer, Call Return, and Call Waiting features.

Call Transfer

Call Transfer allows a user, on any existing two-party call, to place the existing call on hold and originate another call to a third party. The user may consult privately or connect the original call to the third party.

Call Return

Call Return allows the subscriber to place a call back to the last number that called her. Call Return can be either a core system feature, with the user required to dial a code such as *69 , or a set-based feature allowing the user to select from a list of callers.

Call Waiting (CW)

Call Waiting notifies a telephone user, who is on an established call, that an additional external call has been presented and is waiting to be answered. The waiting call receives normal ringing until it is answered, the incoming calling party abandons the call, or the ringing cycle timer expires and the call is given Call Forward No Answer treatment (if applicable). On some phones, only one Call Waiting call can be present at a time. Additional calls are handled with Busy treatment (CFB, if applicable). Implementation of Call Waiting requires support from the phone sets.

Cancel Call Waiting (CCW)

Otherwise known as Do Not Disturb , Cancel Call Waiting allows the subscriber to dial a feature activation code prior to making a call. For the duration of the subsequent call, the Call Waiting feature will be ...

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