voiceoverip

Voice over IP (VoIP) refers to technologies that carry voice and multimedia sessions over IP networks, instead of the traditional public switched telephone network (PSTN). In VoIP, analog voice is digitized, encoded, and packetized for transmission over the Internet or other IP networks. Signaling protocols set up and tear down calls, while the media itself is conveyed as real-time data packets.

Signaling options include SIP (Session Initiation Protocol) and H.323, with SIP widely used in many enterprise and consumer deployments. Media transport relies on RTP (Real-time Transport Protocol), often used with SRTP for encryption. Common codecs include G.711, G.729, G.722, and Opus. VoIP can terminate on IP endpoints or through gateways that connect to the PSTN or other networks.

Architecture typically comprises IP phones or soft clients, a call-control server or PBX, and media gateways or transcoding resources. Endpoints may depend on quality of service (QoS) mechanisms, sufficient bandwidth, and low latency to maintain call quality; NAT traversal and firewall configuration are common technical challenges.

Benefits of VoIP include reduced operating costs, scalability, and integration with data networks and collaboration tools. Limitations include dependence on reliable network infrastructure, potential security risks, and regulatory considerations. Security measures commonly employed include TLS for signaling and SRTP for media, along with strong authentication and access controls to mitigate eavesdropping, tampering, and fraud.