The full form of VoIP is Voice over Internet Protocol. It’s used on Computing ,Protocols in Worldwide

Voice over Internet Protocol (VoIP) is a form of communication protocol that allows you to make phone calls over Internet Protocol (IP) networks, such as the Internet, instead of typical analog telephone lines.

Voice over Internet Protocol (VoIP), also called IP telephony, is a method and group of technologies for the delivery of voice communications and multimedia sessions over Internet Protocol (IP) networks, such as the Internet. The terms Internet telephony, broadband telephony, and broadband phone service specifically refer to the provisioning of communications services (voice, fax, SMS, voice-messaging) over the public Internet, rather than via the public switched telephone network (PSTN), also known as plain old telephone service (POTS).