SIP calling uses Session Initiation Protocol, the standard that handles the setup, management, and teardown of a voice session over IP. It is the signaling layer beneath most business VoIP.
SIP keeps voice, video, and messaging on one open standard, which is why it underpins SIP trunking and most modern phone systems.
Frontdesk gives you a business number answered by an AI receptionist that picks up every call, qualifies the caller, books the appointment, and logs the whole conversation to your CRM.