Update: We're in the last throes of winter break 2019, which means most Ars' home office phones can stay dormant for a few more days. As such, we've been resurfacing a few classics from the ...

Session Initiation Protocol (SIP) is a signaling protocol that is used to set up, modify, and terminate a session between two endpoints. SIP can be used to set up a two-party call, a multi-party call, ...