142.0.0.0 = masked public IP (Remote IP phone)
67.0.0.0 = masked public IP (Asterisk IP)
10.0.2.106 = internal IP (Remote IP phone)
192.168.1.87 = Asterisk Interface IP (not doing NAT - pub IP is bound directly to interface also)

U(17) 2007/07/25 10:09:57.629261 192.168.1.87:5060 -> 142.0.0.0:37486
OPTIONS sip:394@10.0.2.106:5060;line=jon6j4kb SIP/2.0.
Via: SIP/2.0/UDP 67.0.0.0:5060;branch=z9hG4bK69c9301f;rport.
From: "NotProvided" <sip:NotProvided@67.0.0.0>;tag=as00e35002.
To: <sip:394@10.0.2.106:5060;line=jon6j4kb>.
Contact: <sip:NotProvided@67.0.0.0>.
Call-ID: 647d7a6f1216f71a5c67076d4ca9d622@67.0.0.0.
CSeq: 102 OPTIONS.
User-Agent: Asterisk PBX.
Max-Forwards: 70.
Date: Wed, 25 Jul 2007 15:09:53 GMT.
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY.
Content-Length: 0.
.


I(1) 2007/07/25 10:09:57.729358 142.0.0.0 -> 192.168.1.87 3:3
....E.."..@./..H...W.......n..U.OPTIONS sip:394@10.0.2.106:5060;line=jon6j4kb SIP/2.0.
Via: SIP/2.0/UDP 67.0.0.0:5060;branch=z9hG4bK69c9301f;rport.
From: "NotProvided" <sip:NotProvided@67.0.0.0>;tag=as00e35002.
To: <sip:394@10.0.2.106:5060;line=jon6j4kb>.
Contact: <sip:NotProvided@67.0.0.0>.
Call-ID: 647d7a6f1216f71a5c67076d4ca9d622@67.0.0.0.
CSeq: 102 OPTIONS.
User-Agent: Asterisk PBX.
Max-Forwards: 70.
Date: Wed, 25 Jul 2007 15:09:53 GMT.
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY.
Content-Length: 0.
.