SIP (Session Initiated Protocol, or Session Initiation Protocol), is  a signaling protocol for Internet conferencing, telephony, presence, events notification and instant messaging. The protocol initiates call setup, routing, authentication and other feature messages to end points within an IP domain.

In this chapter we will cover:

- General

- NAT

- Security

- RTP

- DTMF

- Misc

- Authentication

- Registration

- MWI

- Subscriptions

- Domains

- Codecs

- Additional config