What type of communication method is primarily used for internet-based calls?

The primary communication method used for internet-based calls is Voice over Internet Protocol (VoIP). This technology allows voice communications to be transmitted over the internet rather than through traditional telephone networks. VoIP converts voice signals into digital data packets, which are then sent through the internet and reassembled at the receiving end. This method is favored for its efficiency, cost-effectiveness, and ability to integrate with various multimedia services, such as video calls and messaging.

In contrast, ISDN (Integrated Services Digital Network) is a circuit-switched telephone network system that provides voice and data services but is not primarily internet-based. POTS (Plain Old Telephone Service) refers to the traditional landline telephone service, which operates via analog signals rather than digital ones. Cellular communication uses radio signals to connect mobile devices to the network but does not rely on internet protocols for the voice call setup and transmission. Therefore, VoIP stands out as the correct answer for internet-based communication due to its digital and internet-oriented nature.