Time and technology, however, have changed the consumer telephony landscape, with the flag-bearer being the Open-Standards-based IP PBX. The point of the “IP” in this new era is that the phone calls are delivered using the Internet Protocol as the underlying transport technology.
PBX stands for Private Branch Exchange, which is a private telephone network used within a company or organization. The users of the PBX phone system can communicate internally (within their company) and externally (with the outside world), using different communication channels like Voice over IP, ISDN or analog. A PBX also allows you to have more phones than physical phone lines (PTSN) and allows free calls between users. Additionally, it provides features like transfer calls, voicemail, call recording, interactive voice menus (IVRs) and call queues.
Traditional PBXs would have their own proprietary phones, such that there would be a way to re-use these phones with a different system. This means that we either have system-lock-in (we are bound to the same system because changing system means also changing phones, which makes it prohibitively expensive to break away) or vendor-lock-in (we are bound to the same vendor because the phones are only usable with systems from the same vendor, sometimes only within a particular range of systems).
Time and technology, however, have changed the consumer telephony landscape, with the flag-bearer being the Open-Standards-based IP PBX. The point of the “IP” in this new era is that the phone calls are delivered using the Internet Protocol as the underlying transport technology.
PBX phone systems are available as hosted or virtual solutions and as on-premise solutions to be run on your own hardware.
his image gives us an idea of what an IP-PBX system allows in terms of connectivity and reachability.
With a traditional PBX, you are typically constrained to a certain maximum number of outside telephone lines (trunks) and to a certain maximum number of internal telephone devices or extensions. Users of the PBX phone system (phones or extensions) share the outside lines for making external phone calls.
Switching to an IP PBX brings with it many benefits and opens up possibilities, allowing for almost unlimited growth in terms of extensions and trunks, and introducing more complex functions that are more costly and difficult to implement with a traditional PBX, such as:
* Ring Groups
* Queues
* Digital Receptionists
* Voicemail
* Reporting
IP PBX: How an IP PBX / VoIP Phone System Works
A VoIP Phone System / IP PBX system consists of one or more SIP phones / VoIP phones, an IP PBX server and optionally includes a VoIP Gateway. The IP PBX server is similar to a proxy server: SIP clients, being either soft phones or hardware based phones, register with the IP PBX server, and when they wish to make a call they ask the IP PBX to establish the connection. The IP PBX has a directory of all phones/users and their corresponding SIP address and thus is able to connect an internal call or route an external call via either a VoIP gateway or a VoIP service provider to the desired destination.
At the center we have, the IP PBX. Starting from the bottom, we see the Corporate Network. This is the company’s local network. Through that network, Computers running SIP clients such as the softphones, and IP Phones connect directly to the PBX. On the left, we see the company’s router/firewall connected to the internet. From there it can connect to remote extensions in the form of computers running the softphones,
