Here is a ten-minute video tutorial explaining what SIP is, how SIP works and what SIP does… plus a peek at the Future: the awesome call disposition rules that you will be able to set up for incoming calls: where to send a call based on who is calling, where you are, what device you are using, time of day and any other conditions you want to specify.
tutorial on SIP and call setup flow for VoIP
You can also watch this tutorial on YouTube.
SIP and Voice over IP call setup is explained like this in:
• Course 130 Voice over IP, SIP, Security, 5G and IoT (Thursday and Friday of BOOT CAMP )
• DVD-Video Course V10 Understanding VoIP 3 , and
• Telecom 101 textbook .