Patent ID: 6396905
Filing Date: 2002-05-28
Classification: H04Q

Abstract:
A telecommunication system, comprising:a private branch exchange that connects a call initiated from a source telephone to a destination telephone over one of a number of trunk groups providing access to a number of different public network carrier systems; a central processing unit within the private branch exchange that searches the number of trunk groups and selects one of the number of trunk groups to carry the call, said central processing unit monitoring the call for call progress messages transmitted by the network carrier system accessed by the selected trunk group and searches the trunk groups not previously searched to locate another trunk group that accesses another network carrier system in response to a call progress message received indicating that the call could not be completed by the network carrier system accessed by the first selected trunk group; wherein the central processing unit continues to monitor the call until a call progress message is received indicating that the call could not be completed by the network carrier system accessed by the selected trunk group or until the call is answered.