NOTIFY sip:PHONE-EXTENSION@ASTERISK-IP-ADDR SIP/2.0
From: "Anonymous"<sip:Anonymous@SENDER-IP-ADDR:5065>;tag=b6feff0-0-13c9-50022-e04-aed0a15-e04
To: <sip:PHONE-EXTENSION@ASTERISK-IP-ADDR:5060>
Call-ID: b6feff0-0-13c9-50022-e04-2c8c0a3c-e04
CSeq: 3 NOTIFY
Via: SIP/2.0/UDP SENDER-IP-ADDR:5060;branch=z9hG4bK-e04-36c083-2220f043
Max-Forwards: 70
Supported: replaces
Contact: <sip:Anonymous@SENDER-IP-ADDR>
Event: message-summary
Content-Type: application/simple-message-summary
Content-Length: 47

Messages-Waiting:yes
Voice-Message: 1/0 (0/0).