In the world of VoIP, SIP works primarily in which layer of the OSI model?

In the world of VoIP, SIP works primarily in which layer of the OSI model?

• Layer 4: transportation layer
• Layer 5: session layer
• Layer 2: data link layer
• Layer 7: application layer 

EXPLANATION

A Session Initiation Protocol (SIP) operates on the application layer. The basic purpose of SIP is to establish communications over the internet.
These communications might include video conferencing, online gaming or audio calls. It makes use of the idea of Voice over IP (VoIP) to achieve this purpose. It can create, modify and terminate these communication sessions. However, SIP also makes use of other transfer protocols such as TCP and UDP and does not operate entirely on its own.