Проблемы с входящими по SIP, Bad Request в ответ на INVITE Опции

[mike1]

Столкнулся с такой проблемой: периодически не проходят входящие звонки по SIP. В tcpdump это выглядит следующим образом:

INVITE sip:3251XXX@80.69.180.XXX:5060;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 212.17.0.XXX:5060;branch=z9hG4bK00ec651a;rport
Max-Forwards: 70
From: "9139009XXX" <sip:9139009XXX@212.17.0.XXX>;tag=as6fa6667a
To: <sip:3251XXX@80.69.180.XXX:5060;transport=UDP>
Contact: <sip:9139009XXX@212.17.0.XXX:5060>
Call-ID: 6e8631dc6fc35370244137f6286d0404@212.17.0.XXX:5060
CSeq: 102 INVITE
User-Agent: FPBX-2.8.1(1.8.20.0)
Date: Mon, 04 Aug 2014 10:43:12 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH
Supported: replaces, timer
Content-Type: application/sdp
Content-Length: 280

v=0
o=root 595865158 595865158 IN IP4 212.17.0.XXX
s=Asterisk PBX 1.8.20.0
c=IN IP4 212.17.0.XXX
t=0 0
m=audio 10712 RTP/AVP 8 0 3 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:3 GSM/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv
SIP/2.0 400 Bad Request
From: "9139009XXX"<sip:9139009XXX@212.17.0.XXX>;tag=as6fa6667a
To: <sip:3251XXX@80.69.180.XXX:5060;transport=UDP>;tag=23f7410-320ea8c0-13c4-65014-6678d-291a294b-6678d
Call-ID: 6e8631dc6fc35370244137f6286d0404@212.17.0.XXX:5060
CSeq: 102 INVITE
Via: SIP/2.0/UDP 212.17.0.XXX:5060;rport=5060;branch=z9hG4bK00ec651a
Content-Length: 0

ACK sip:3251XXX@80.69.180.XXX:5060;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 212.17.0.XXX:5060;branch=z9hG4bK00ec651a;rport
Max-Forwards: 70
From: "9139009XXX" <sip:9139009XXX@212.17.0.XXX>;tag=as6fa6667a
To: <sip:3251XXX@80.69.180.XXX:5060;transport=UDP>;tag=23f7410-320ea8c0-13c4-65014-6678d-291a294b-6678d
Contact: <sip:9139009XXX@212.17.0.XXX:5060>
Call-ID: 6e8631dc6fc35370244137f6286d0404@212.17.0.XXX:5060
CSeq: 102 ACK
User-Agent: FPBX-2.8.1(1.8.20.0)
Content-Length: 0

INVITE sip:3251XXX@80.69.180.XXX:5060;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 212.17.0.XXX:5060;branch=z9hG4bK698ac487;rport
Max-Forwards: 70
From: "913900XXX" <sip:9139009XXX@212.17.0.XXX>;tag=as07be447c
To: <sip:3251XXX@80.69.180.XXX:5060;transport=UDP>
Contact: <sip:9139009XXX@212.17.0.XXX:5060>
Call-ID: 6e17cd6231feafa214a948f45e9cd88d@212.17.0.XXX:5060
CSeq: 102 INVITE
User-Agent: FPBX-2.8.1(1.8.20.0)
Date: Mon, 04 Aug 2014 10:43:22 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH
Supported: replaces, timer
Content-Type: application/sdp
Content-Length: 282

v=0
o=root 1030384154 1030384154 IN IP4 212.17.0.XXX
s=Asterisk PBX 1.8.20.0
c=IN IP4 212.17.0.XXX
t=0 0
m=audio 19420 RTP/AVP 8 0 3 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:3 GSM/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv
INVITE sip:3251XXX@80.69.180.XXX:5060;transport=UDP SIP/2.0
Via: SIP/2.0/UDP 212.17.0.XXX:5060;branch=z9hG4bK698ac487;rport
Max-Forwards: 70
From: "9139009XXX" <sip:9139009XXX@212.17.0.XXX>;tag=as07be447c
To: <sip:3251XXX@80.69.180.XXX:5060;transport=UDP>
Contact: <sip:9139009XXX@212.17.0.XXX:5060>
Call-ID: 6e17cd6231feafa214a948f45e9cd88d@212.17.0.XXX:5060
CSeq: 102 INVITE
User-Agent: FPBX-2.8.1(1.8.20.0)
Date: Mon, 04 Aug 2014 10:43:22 GMT
Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, SUBSCRIBE, NOTIFY, INFO, PUBLISH
Supported: replaces, timer
Content-Type: application/sdp
Content-Length: 282

v=0
o=root 1030384154 1030384154 IN IP4 212.17.0.XXX
s=Asterisk PBX 1.8.20.0
c=IN IP4 212.17.0.XXX
t=0 0
m=audio 19420 RTP/AVP 8 0 3 101
a=rtpmap:8 PCMA/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:3 GSM/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=ptime:20
a=sendrecv

Т.е. ЛыЖа на INVITE дает отлуп Bad Request. В чем проблема/причина?