An integrated voice 
gateway system for use within a company which can 
route a voice 
telephone call between parties at two different locations over an IP network or over the PST NETWORK. The 
system can 
route a voice 
telephone call from a first location within the 
system to a second location within the 
system via the IP network, and then from the second location to a third location via the PST NETWORK. The integrated voice 
gateway system includes a gateway 
server which serves as an 
intranet / Internet 
telephony gateway. The gateway 
server routes intra-company voice or 
facsimile (fax) calls, over the company's 
intranet or the public Internet. The gateway 
server provides an alternate voice network to the PST NETWORK for a company. This alternate network is provided at a much lower cost. The gateway server is a combination of hardware and 
software components which reside on a PC server platform. The gateway server is coupled to a customer premise telephone system, i.e. a PBX via a T1 or E1 
trunk for larger systems, or an analog 
trunk for smaller systems. The gateway server is coupled to the company's 
intranet via 
industry standard connections. The gateway servers in a multi-site company are coupled together via the company's intranet or 
wide area network (WAN) into a gateway network. The gateway server uses PBX call status links to provide many unique and useful features which are otherwise unavailable. The gateway server uses T1 inband ANI, PRI, QSIG or 
industry standard CTI applications 
programming interfaces (API) and works with any PBX which supports any of these call status links. The gateway server is equipped with a 
database of user and gateway objects and attributes, and provides many unique features including caller's name based on caller phone number, address translation, gateway 
network routing information, 
user authentication, etc. This 
database can be integrated with 
industry standard enterprise 
directory services systems including any 
directory which supports the 
Lightweight Directory Access Protocol (X.500) (LDAP) interface.