What are the SIP messages for a regular call?

What are the SIP messages for a regular call?

SIP Requests and SIP Responses

  • INVITE: Establishes a session.
  • ACK: Confirms INVITE request.
  • BYE: Ends a session.
  • CANCEL: Cancels establishing a session.
  • REGISTER: Communicates user location.
  • OPTIONS: Communicates info about the calling/receiving SIP phones’ capabilities.

How do SIP calls work?

SIP protocol SIP works by sending messages from one SIP address to another. These messages are typically voice calls. However, SIP also powers messages in the form of video calling and instant messaging. SIP is an over-the-internet exchange of information.

What is SIP call signaling?

What is SIP? The Session Initiation Protocol is a signaling protocol that enables the Voice Over Internet Protocol (VoIP) by defining the messages sent between endpoints and managing the actual elements of a call. SIP supports voice calls, video conferencing, instant messaging, and media distribution.

Is SIP a session layer protocol?

Session Initiation Protocol (SIP) is one of the most common protocols used in VoIP technology. It is an application layer protocol that works in conjunction with other application layer protocols to control multimedia communication sessions over the Internet.


On a technical level, SIP carries VoIP traffic over either UDP or TCP on ports 5060 or 5061. By comparison, browsing the web typically occurs over ports 80 and 443.

What does SIP mean in SIP call flow?

“SIP call flow” is a fancy term to describe how a SIP call works. SIP Requests and SIP Responses When making a SIP call, your SIP device sends requests to the endpoint (the other SIP device). A request needs an answer.

Who are the end users of a SIP call?

Below diagram illustrates a successful gateway-to-Cisco SIP IP phone call setup and disconnect. In this scenario, the two end users are User A and User B. User A is located at PBX A. PBX A is connected to Gateway 1 (SIP Gateway) via a T1/E1.

What is the role of CallManager 5.x in SIP?

CallManager 5.x supports SIP phones and is an integral part of a SIP network. It can play different roles, such as registrar server and B2BUA. Figure 4-4 illustrates a call flow scenario with CallManager acting as a B2BUA. Figure 4-4 Call Flow with CallManager 5.x In Figure 4-4, a SIP phone is registered to a CallManager.

How does a SIP call start in PBX a?

1. Call Setup is initiated between PBX A and Gateway 1. The Call Setup includes the standard transactions that take place as User A attempts to call User B. 2. Gateway 1 maps the SIP URL phone number to a dial peer. The dial peer includes the IP address and the port number of the SIP-enabled entity to contact.

Share this post