SIP Call session between 2 phones

• The calling phone sends out an invite
• The called phone sends an information response 100 – Trying – back.
• When the called phone starts ringing a response 180 – Ringing – is sent back
• When the caller picks up the phone, the called phone sends a response 200 – OK
• The calling phone responds with ACK – acknowledgement
• Now the actual conversation is transmitted as data via RTP
• When the person calling hangs up, a BYE request is sent to the calling phone
• The calling phone responds with a 200 – OK.