Method for transferring calls between PBX telephone and SIP client

Abstract

This invention integrates instant messaging, presence, and other collaborative capabilities with conventional PBX functionality through use of a PBX-Messaging Integration Client (PMIC). The invention in its several embodiments features a method and system for using the PMIC-based computer interface to perform off-hook/on-hook presence notification for a PBX phone, establish media sessions concurrent with PBX telephonic communication, execute custom call treatment in conjunction with a PBX phone, implement call transfer capability between a PBX phone and numerous other devices, and provide PBX call control. The PBX is generally enabled with computer telephony integration (CTI) and, depending on the embodiment, a Voice-over-Internet Protocol (VoIP) such as Session Initiation Protocol (SIP). The invention empowers enterprise workers with a diverse, unified and integrated set of both PBX functions and SIP-based collaboration tools.

1 . A call transfer method for a first computer interface operatively coupled to a system comprising a private branch exchange (PBX) and a first PBX phone, the call transfer method comprising the steps of: 
 transmitting to the PBX a first message for transferring a telephone call associated with the first PBX phone;    establishing a voice-over-IP session between the PBX and the first computer interface; and    replacing the telephone call to first PBX phone with a call to the first computer interface via the voice-over-IP session.    
     
     
         2 . The call transfer method of  claim 1 , wherein the first message is a CTI event message.  
     
     
         3 . The call transfer method of  claim 1 , wherein the first message comprises a universal resource identifier associated with the first computer interface.  
     
     
         4 . The call transfer method of  claim 1 , wherein the step of establishing a voice-over-IP session comprises the steps of: 
 receiving a voice-over-IP session request message from the PBX; and    transmitting a voice-over-IP session acceptance message.    
     
     
         5 . The call transfer method of  claim 4 , wherein the session request message is an SIP INVITE message and the session acceptance message is an SIP OK message.  
     
     
         6 . A call transfer method for a first computer interface operatively coupled to a system comprising a private branch exchange (PBX) and a first PBX phone, the call transfer method comprising the steps of: 
 transmitting to the PBX a first message for transferring a voice-over-IP session associated with the first computer interface and PBX; and    establishing a telephone call associated with the first PBX phone; and    terminating the voice-over-IP session between the PBX and the first computer interface.    
     
     
         7 . The call transfer method of  claim 6 , wherein the first message is a CTI event message.  
     
     
         8 . The call transfer method of  claim 6 , wherein the first message comprises an extension number associated with the first PBX phone.  
     
     
         9 . The call transfer method of  claim 6 , wherein the step of establishing the voice-over-IP session comprises the step of transmitting a private digital signals and voice (PDSV) signal to the first PBX phone.