Patent ID: 7616747

Claim:
A method of controlling a telecommunications network comprising the steps of: recognizing a busy condition of a subscriber line; initiating a first call to said subscriber line in response to recognizing the busy condition, including transmitting a first call set-up message indicating a first special calling party number to said subscriber line; detecting a trigger when said first call reaches a switching point in the telecommunications network; in response to detecting the trigger, transmitting a first query message to a control point in the telecommunications network, said first query message including said special calling party number; receiving said first query message at said control point; storing an indicator of said condition in response to receiving said first special calling party number; recognizing a change of said condition; initiating a second call in response to recognizing the change of said condition, including transmitting a second call set-up message indicating a second special calling party number; detecting a trigger when said second call reaches a switching point in the telecommunications network; transmitting a second query message including said second special calling party number; receiving said other query message including said second special calling party number; and updating said indicator of said condition in response to receiving said second special calling party number.