IP telephony (Internet Protocol telephony) is a general term used to describe voice and fax using the Internet Protocol. It's used interchangeably with the other mainstream telecoms acronyms VoIP and UC. This form of digital communication is much more efficient and resilient than SS7. The PSTN (The aggregate of telecommunications networks) is moving to digital IP based technologies and by 2025 the PSTN with the United Kingdom should be completely IP based.
Using IP data connectivity, calls travel as packets of data in the same way your mobile 4g or your home broadband works. This avoids the bottlenecks of the analogue based connections and offers scalability relative to the available bandwidth. According to global internet firm Akamai the average internet connection in the UK is 16.1Mbps
This average speed of 16.1Mbps crudely translates to circa 100 concurrent IP voice calls using the G.711 codec (PSTN Quality Equivalent). There are of course major enhanced capabilities such as High Definition HD audio quality, video and instant messaging.
Unlike traditional phone services, IP telephony services when used in conjunction with a Cloud Telecommunications Provider can be routed anywhere that offers IP connectivity, this means that your service is dynamic and can be accessed from anywhere and routed to anywhere.
SIP Trunking is simply a connection between a provider (such as VoiceHost) and an endpoint (such as a SIP compatible telephone or PBX). SIP supports Voice, Video and Instant messaging and calls in and out, flow along the SIP Trunk.
The standards proposed for IP telephony on the PSTN currently open for consultation with the UK regulator Ofcom and the NICC
The Session Initiation Protocol (SIP) is proposed along with the G.711 as the default voice codec for internetworking.
You can use a physical handset or a computer program/application to make and receive calls. The SIP hardware market is mature now with major brands offering analogue alternatives at competitive prices. Apps from computers and smartphones are also available. See the VoiceHost store store.voicehost.co.uk for further information.