This is what I see on console when I activate debugging. I guess those messages are OPTIONS requests that asterisk is sending to the other peer, not the ones that the other peer is sending.
asterisk -rvvvvvvvvvv -gggggggggg
[size=85][code]
CLI> sip set debug ip 1.1.1.1
SIP Debugging Enabled for IP: 1.1.1.1
Reliably Transmitting (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK2a5c5f0f;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as75134caa
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 6e9dc6c83cfb15ec55ec065f58e99ad8@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:34:59 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Retransmitting #1 (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK2a5c5f0f;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as75134caa
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 6e9dc6c83cfb15ec55ec065f58e99ad8@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:34:59 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Retransmitting #2 (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK2a5c5f0f;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as75134caa
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 6e9dc6c83cfb15ec55ec065f58e99ad8@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:34:59 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Reliably Transmitting (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK5612ad9b;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as68350bf8
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 19e63f5b0be91be91dc533b950717151@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:35:11 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Retransmitting #1 (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK5612ad9b;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as68350bf8
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 19e63f5b0be91be91dc533b950717151@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:35:11 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Retransmitting #2 (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK5612ad9b;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as68350bf8
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 19e63f5b0be91be91dc533b950717151@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:35:11 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Reliably Transmitting (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK64efc3f0;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as3cda0984
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 342f1b623e7031410f7f000b21bf5c2d@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:35:23 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
Retransmitting #1 (no NAT) to 1.1.1.1:5060:
OPTIONS sip:1.1.1.1 SIP/2.0
Via: SIP/2.0/UDP 2.2.2.2:5060;branch=z9hG4bK64efc3f0;rport
Max-Forwards: 70
From: “Unknown” sip:Unknown@2.2.2.2;tag=as3cda0984
To: sip:1.1.1.1
Contact: sip:Unknown@2.2.2.2
Call-ID: 342f1b623e7031410f7f000b21bf5c2d@2.2.2.2
CSeq: 102 OPTIONS
User-Agent: Asterisk PBX 1.6.0.25
Date: Thu, 04 Nov 2010 11:35:23 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO
Supported: replaces, timer
Content-Length: 0
[/code][/size]