The Linux based Open Source Software Asterisk has become the de facto standard in modern VoIP PBX systems. Because of its powerful and flexible structure Asterisk is also being used as the VoIP engine in commercial PBX products, partly because some pbx manufacturers have realized that it would not make much sense to compete against the development momentum of this open source project and end up having an expensive look-alike that no one wants to write interface software for.
The flexibility of Asterisk comes with a price, though. There is no user friendly interface included and the command language and syntax have a very steep learning curve.
Even though some VoIP enthusiasts are configuring their Asterisk pbx box from the command line interface, this is not practical for a commercial product. Managing a pbx system this way would be just as absurd as trying to sell a fax machine that needs a computer science diploma to operate.
O.K, this fax machine comparison is not quite fair because pbx systems in general need much more complex configuration, but this is why the Asterisk PBX Manager Web GUI was developed. It allows configuring and operating an Asterisk based VoIP system as conveniently as with conventional pbx boxes but leaving the door open for much more sophisticated telephony and interface functions.
Asterisk is basically a a complete PBX engine in software. It runs on Linux, BSD and MacOSX and provides all of the features you would expect from a PBX and more. Asterisk does voice over IP in many protocols, and can interoperate with almost all standards-based telephony equipment using relatively inexpensive hardware.
Even though it behaves as a classical voice exchage there is a major difference in dataflow when using the popular SIP protocol for connecting telephones: In principle there is no difference of a telefone being external or internal. This means that a person using a mobile IP telephone, for example a SIP softphone installed on a notebook or pda, this telephone will ring no matter where it is globally located. When using the popular SIP protocol it is even possible to have all voice or video data flowing directly between caller and callee if both are located somewhere external to the Asterisk pbx. This is in contrast to classical PBXes where the voice data stream must always flow physically through them.
Connecting branch offices and home offices to the company network is one of the most prominent selling points of VoIP technology. This is not only because of the rather obvious cost savings that can be expected, but also because of the long term advantage of having a clean and straightforward integration of all voice endpoints companywide.
When migrating classical PBXes to Voice over IP they become part of the existing IT infrastructure, similar to a mail or file server. While saving 50% of all cabling costs it is now possible to more easily integrate the pbx system into the already existing management, backup and usv infrastructure.