Session Initiation Protocol consists of two major components: the _____________ and __________________.

A.
User Agent Client, User Agent Server

B.
User Agent Client, User Agent Service

C.
User Client, User Service

D.
User Urgent Client, User Urgent Server

Explanation:
SIP consists of two major components: the User Agent Client (UAC) and
User Agent Server (UAS). The UAC is the application that creates the SIP requests
for initiating a communication session. UACs are generally messaging tools and
soft-phone applications that are used to place VoIP calls. The UAS is the SIP
server, which is responsible for handling all routing and signaling involved in VoIP
calls.