PBX stands for Private Branch Exchange, which is a private telephone network used within a company.
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.
This 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.
An IP-PBX 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
- Digital Receptionists