Patent ID: 6816587
Filing Date: 2004-11-09
Classification: H04M,H04Q,Y10S

Abstract:
A method for establishing a virtual private line between a first private branch exchange (PBX) and a second PBX through an Integrated Services Digital Network (ISDN) to connect a first terminal accommodated in the first PBX and a second terminal accommodated in the second PBX, comprising the steps of:at the first PBX having a first digital interface trunk circuit connected to the ISDN, a) generating an SS7 (common channel signalling system No. 7) message in response to a call originated by the first terminal; b) generating an ISDN message having the SS7 message included therein; and c) sending the ISDN message to the second PBX on a D channel of the first digital interface trunk circuit, and at the second PBX having a second digital interface trunk circuit connected to the ISDN, d) receiving the ISDN message from the first PBX on a D channel of the second digital interface trunk circuit; and e) reading the SS7 message from the ISDN message received to establish the virtual private line between the first and second PBXs, allowing the first and second terminals to communicate with each other through the virtual private line, wherein the step (b) comprises the steps of: b.1) generating an ISDN message for the SS7 message; b.2) setting a virtual private line flag indicating that the SS7 message is used for virtual private line connection; b.3) storing the virtual private line flag and the SS7 message in a facility information element of the ISDN message.