IPPBXs

An IP PBX (Internet Protocol Private Branch Exchange), commonly called an IPPBX, is a private telephone switching system that uses IP networks and Voice over IP (VoIP) protocols to route calls between internal extensions and to external networks.

In an IPPBX, call processing is performed by a central server or cluster; user devices include IP phones, softphones, or mobile apps. The system connects to the outside world via SIP trunks or gateways that link to the public switched telephone network (PSTN) or to other VoIP providers. Core features typically include auto-attendant, voicemail, call routing, interactive voice response (IVR), conference calling, call recording, and presence.

Deployment models include on-premises IPPBX appliances, hosted or cloud-based services, or hybrid configurations that blend local control with external hosting. Scalability is achieved by adding extensions, trunks, or virtualized resources, allowing organizations to adjust capacity as needs change.

Advantages include potential cost reductions from using packetized IP transport, scalable extensions and trunks, centralized management, easy deployment of new features, and support for remote or mobile workers and integration with business applications such as customer relationship management (CRM) systems.

Interoperability and security considerations center on compatibility with traditional PSTN services through gateways and SIP trunks, the use of SIP as a standard signaling protocol, and the need for quality of service (QoS) and security measures such as TLS for signaling and SRTP for media. Proper NAT traversal and firewall rules are also important for protecting communications.

IPPBX systems are commonly adopted by small and medium-sized businesses and larger enterprises, including contact centers, to consolidate telephony, unified communications, and voicemail into a single platform.