What is VoIP full form?

VoIP stands for voice communication over Internet Protocol.   It is the group of technologies that provides voice and multimedia sessions over the IP network. The full form of VoIP is Voice Over Internet Protocol (IP).  IP telephony is a relatively new communication system for voice.  In legacy telecom network SS7 protocol is the network, which consists of voice over E1/T1 TDM trunks.  The telephone exchanges are connected to each other via ss7 trunks.  Each trunk has multiple voice channels. VOIP exchanges are connected to each other over the IP network.  SIP trunks connect telephone exchanges.

SIP or Session Initiation Protocol is the signaling protocol for setup a voice session. Even it has more functionalities than just setup voice, Fax, Video calls, etc.  For actual voice packets, the RTP protocol is used.  To set up a media session over IP, the SIP Session setup message (INVITE), carries media session information in payload. SDP or session description protocol defines the properties and parameters for an actual voice session. Once signaling is done for voice/media actual data packets flow. To terminate a session any end can close. SIP BYE message is used to terminate an ongoing session.

VoIP opens new business models. The business is easy to start. One can be a reseller of voice routes, Virtual Numbers, etc.  With the IP telephone now it is easy to connect with mobile operators for new services. This enables value-added service providers (VAS), to deploy new voice-based services easily and quickly.

The full form is Voice over Ip. So all communication is over the IP network. This enables to use of already deployed IP network capabilities.  An IP network uses DNS servers, switches, routers, etc.  Along with IP, the SIP protocol uses UDP over  IP.