Overview
IP phones are telephones that carry voice as data packets across an Internet Protocol (IP) network instead of using the traditional public switched telephone network. They connect to a VoIP service (VoIP provider) over networks such as the internet or a private LAN. This approach can reduce per-call costs and enables integration with other data services and applications.
Components and operation
Physically, an IP phone resembles a conventional desk handset but includes an Ethernet port, a network interface controller and embedded firmware. Many deployments also use softphones—software-based phones that run on PCs or mobile devices. To communicate with legacy analog or TDM systems, IP telephony relies on gateways or analog telephone adapters that translate between packetized voice and circuit-switched formats.
Common features
- Signalling and codecs: implementations typically use SIP or other signalling protocols and a selection of voice codecs for compression and quality trade-offs.
- Business features: voicemail, caller ID, call transfer, conferencing, hold, call recording and directory integration.
- Network and security: support for Power over Ethernet (PoE), VLANs, Quality of Service (QoS) settings and optional encryption such as SRTP/TLS for secure media and signalling.
History and development: IP telephony emerged from early packet-voice experiments in the 1990s and matured as broadband, standardized protocols and cheaper IP infrastructure became widespread. Standardization and improved interoperability helped adoption in enterprises and contact centers.
Uses and distinctions: IP phones are widely used in offices, call centers and remote work setups. Compared with analog phones, they offer tighter integration with computer applications, unified communications and presence information. Key considerations for deployments include network capacity, latency and jitter management, interoperability with public telephone networks, and security measures to protect signalling and media.