Система такова:

софтфон <1> нат <2> openser <3> cisco <4> gateway <5> упатс <6> atc <7> телефон

при звонке с сотфона на телефон - сигнализация ходит, голос тоже, при отбое с любой стороны соединение успешно завершается:
U 89.221.48.250:5060 -> 89.221.63.10:5060
  INVITE sip:5031112@89.221.63.10:5060;transport=udp SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1540;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branc
  h=z9hG4bK573.565bb2d3.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK241944..To: <sip:5031112@89.221.48.250>..From:
   "4926" <sip:4926@89.221.48.250>;tag=1540..Call-ID: 1228891636-1944-EVD@192.168.0.7..CSeq: 142 INVITE..Max-Forwards: 19..User-Agent: Express Talk 2.02..
  Contact: <sip:4926@89.221.63.16:5070>..Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, INFO, REFER, NOTIFY..Supported: replaces..Content-Type: application/sdp
  ..Content-Length: 313....v=0..o=- 871554331 871554359 IN IP4 192.168.0.7..s=Express Talk..c=IN IP4 89.221.48.250..t=0 0..m=audio 60800 RTP/AVP 0 8 96 3
  13 101..a=rtpmap:0 PCMU/8000..a=rtpmap:8 PCMA/8000..a=rtpmap:96 G726-32/8000..a=rtpmap:3 GSM/8000..a=rtpmap:13 CN/8000..a=rtpmap:101 telephone-event/800
  0..a=fmtp:101 0-16..a=sendrecv....
#
U 89.221.63.10:5060 -> 89.221.48.250:5060
  SIP/2.0 100 Trying..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK573.565bb2d3.0,SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9h
  G4bK241944..From: "4926" <sip:4926@89.221.48.250>;tag=1540..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..Date: Wed, 10 Dec 2008 07:17:01 GMT..Call
  -ID: 1228891636-1944-EVD@192.168.0.7..Server: Cisco-SIPGateway/IOS-12.x..CSeq: 142 INVITE..Allow-Events: telephone-event..Content-Length: 0....
#
U 89.221.63.10:5060 -> 89.221.48.250:5060
  SIP/2.0 183 Session Progress..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK573.565bb2d3.0,SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;
  branch=z9hG4bK241944..From: "4926" <sip:4926@89.221.48.250>;tag=1540..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..Date: Wed, 10 Dec 2008 07:17:01
   GMT..Call-ID: 1228891636-1944-EVD@192.168.0.7..Server: Cisco-SIPGateway/IOS-12.x..CSeq: 142 INVITE..Allow-Events: telephone-event..Contact: <sip:503111
  2@89.221.63.10:5060>..Record-Route: <sip:89.221.48.250;lr;ftag=1540;nat=yes>..Content-Disposition: session;handling=required..Content-Type: application/
  sdp..Content-Length: 203....v=0..o=CiscoSystemsSIP-GW-UserAgent 4108 8574 IN IP4 89.221.63.10..s=SIP Call..c=IN IP4 89.221.63.10..t=0 0..m=audio 18756 R
  TP/AVP 8 13..c=IN IP4 89.221.63.10..a=rtpmap:8 PCMA/8000..a=rtpmap:13 CN/8000..
#
U 89.221.63.10:5060 -> 89.221.48.250:5060
  SIP/2.0 180 Ringing..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK573.565bb2d3.0,SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9
  hG4bK241944..From: "4926" <sip:4926@89.221.48.250>;tag=1540..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..Date: Wed, 10 Dec 2008 07:17:01 GMT..Cal
  l-ID: 1228891636-1944-EVD@192.168.0.7..Server: Cisco-SIPGateway/IOS-12.x..CSeq: 142 INVITE..Allow-Events: telephone-event..Contact: <sip:5031112@89.221.
  63.10:5060>..Record-Route: <sip:89.221.48.250;lr;ftag=1540;nat=yes>..Content-Length: 0....
#
U 89.221.63.10:5060 -> 89.221.48.250:5060
  SIP/2.0 200 OK..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK573.565bb2d3.0,SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK
  241944..From: "4926" <sip:4926@89.221.48.250>;tag=1540..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..Date: Wed, 10 Dec 2008 07:17:01 GMT..Call-ID:
   1228891636-1944-EVD@192.168.0.7..Server: Cisco-SIPGateway/IOS-12.x..CSeq: 142 INVITE..Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SU
  BSCRIBE, NOTIFY, INFO..Allow-Events: telephone-event..Contact: <sip:5031112@89.221.63.10:5060>..Record-Route: <sip:89.221.48.250;lr;ftag=1540;nat=yes>..
  Content-Type: application/sdp..Content-Length: 203....v=0..o=CiscoSystemsSIP-GW-UserAgent 4108 8574 IN IP4 89.221.63.10..s=SIP Call..c=IN IP4 89.221.63.
  10..t=0 0..m=audio 18756 RTP/AVP 8 13..c=IN IP4 89.221.63.10..a=rtpmap:8 PCMA/8000..a=rtpmap:13 CN/8000..
#
U 89.221.48.250:5060 -> 89.221.63.10:5060
  ACK sip:5031112@89.221.63.10:5060 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1540;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK573.565b
  b2d3.2..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK251944..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..From
  : "4926" <sip:4926@89.221.48.250>;tag=1540..Call-ID: 1228891636-1944-EVD@192.168.0.7..CSeq: 142 ACK..Max-Forwards: 19..User-Agent: Express Talk 2.02..Pr
  oxy-Authorization: Digest username="4926@ch.govorit.ru",realm="ch.govorit.ru",nonce="493f7b9b012ac9cfb7d938b0d0866a070c64c6b2",uri="sip:5031112@89.221.4
  8.250",response="693f2c43fd9d73b96abf5032cef82290",opaque=""..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:5060
  BYE sip:5031112@89.221.63.10:5060 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1540;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK673.3491
  29.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK261944..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..From:
  "4926" <sip:4926@89.221.48.250>;tag=1540..Call-ID: 1228891636-1944-EVD@192.168.0.7..CSeq: 143 BYE..Max-Forwards: 19..User-Agent: Express Talk 2.02..Cont
  ent-Length: 0....
#
U 89.221.63.10:5060 -> 89.221.48.250:5060
  SIP/2.0 200 OK..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bK673.349129.0,SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK26
  1944..From: "4926" <sip:4926@89.221.48.250>;tag=1540..To: <sip:5031112@89.221.48.250>;tag=241A52E2-256E..Date: Wed, 10 Dec 2008 07:17:07 GMT..Call-ID: 1
  228891636-1944-EVD@192.168.0.7..Server: Cisco-SIPGateway/IOS-12.x..Content-Length: 0..CSeq: 143 BYE....

При звонке с телефона на софтфон - тоже все хорошо, за исключением 1 поганости - при отбое со стороны софтфона телефон не отбивается, в сторону упатс по debug isdn q931 - участок <5> обмена нет:

U 89.221.63.10:56340 -> 89.221.48.250:5060
  INVITE sip:4926@89.221.48.250:5060 SIP/2.0..Via: SIP/2.0/UDP  89.221.63.10:5060..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..To: <sip:4926@89.221.4
  8.250>..Date: Wed, 10 Dec 2008 07:19:45 GMT..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..Supported: timer..Min-SE:  1800..Cisco-Guid: 324
  5693305-3317764573-2414607393-2535017042..User-Agent: Cisco-SIPGateway/IOS-12.x..Allow: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIB
  E, NOTIFY, INFO..CSeq: 101 INVITE..Max-Forwards: 6..Timestamp: 1228893585..Contact: <sip:1112@89.221.63.10:5060>..Expires: 180..Allow-Events: telephone-
  event..Content-Type: application/sdp..Content-Length: 250....v=0..o=CiscoSystemsSIP-GW-UserAgent 4914 7514 IN IP4 89.221.63.10..s=SIP Call..c=IN IP4 89.
  221.63.10..t=0 0..m=audio 17796 RTP/AVP 18 8 19..c=IN IP4 89.221.63.10..a=rtpmap:18 G729/8000..a=fmtp:18 annexb=no..a=rtpmap:8 PCMA/8000..a=rtpmap:19 CN
  /8000..
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  SIP/2.0 100 Trying..Via: SIP/2.0/UDP  89.221.63.10:5060;rport=56340..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..To: <sip:4926@89.221.48.250>..Call
  -ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 101 INVITE..Server: OpenSER (1.2.3-notls (i386/freebsd))..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  SIP/2.0 180 Ringing..Via: SIP/2.0/UDP  89.221.63.10:5060;rport=56340..Record-Route: <sip:89.221.48.250;lr;ftag=241CD07A-2596;nat=yes>..To: <sip:4926@89.
  221.48.250>;tag=1542..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 101 INVITE..User
  -Agent: Express Talk 2.02..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  SIP/2.0 180 Ringing..Via: SIP/2.0/UDP  89.221.63.10:5060;rport=56340..Record-Route: <sip:89.221.48.250;lr;ftag=241CD07A-2596;nat=yes>..To: <sip:4926@89.
  221.48.250>;tag=1542..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 101 INVITE..User
  -Agent: Express Talk 2.02..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  SIP/2.0 180 Ringing..Via: SIP/2.0/UDP  89.221.63.10:5060;rport=56340..Record-Route: <sip:89.221.48.250;lr;ftag=241CD07A-2596;nat=yes>..To: <sip:4926@89.
  221.48.250>;tag=1542..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 101 INVITE..User
  -Agent: Express Talk 2.02..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  SIP/2.0 200 OK..Via: SIP/2.0/UDP  89.221.63.10:5060;rport=56340..Record-Route: <sip:89.221.48.250;lr;ftag=241CD07A-2596;nat=yes>..To: <sip:4926@89.221.4
  8.250>;tag=1542..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 101 INVITE..User-Agen
  t: Express Talk 2.02..Contact: <sip:4926@89.221.63.16:5070>..Allow: INVITE, ACK, CANCEL, OPTIONS, BYE, REFER, NOTIFY..Accept: application/sdp..Supported
  : replaces..Content-Type: application/sdp..Content-Length: 181....v=0..o=- 871554331 871554364 IN IP4 192.168.0.7..s=Express Talk..c=IN IP4 89.221.48.25
  0..t=0 0..m=audio 60804 RTP/AVP 8 19..a=rtpmap:8 PCMA/8000..a=rtpmap:19 CN/8000..a=sendrecv....
#
U 89.221.63.10:51161 -> 89.221.48.250:5060
  ACK sip:89.221.48.250:5060;lr;ftag=241CD07A-2596;nat=yes SIP/2.0..Via: SIP/2.0/UDP  89.221.63.10:5060..From: <sip:1112@89.221.63.10>;tag=241CD07A-2596..
  To: <sip:4926@89.221.48.250>;tag=1542..Date: Wed, 10 Dec 2008 07:19:45 GMT..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..Route: <sip:4926@
  89.221.63.16:5070>..Max-Forwards: 6..Content-Length: 0..CSeq: 101 ACK....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  BYE sip:1112@89.221.63.10:56340 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1542;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bKee28.20810
  b41.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK271944..To: <sip:1112@89.221.63.10>;tag=241CD07A-2596..From: <si
  p:4926@89.221.48.250>;tag=1542..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 438 BYE..Max-Forwards: 19..User-Agent: Express Talk 2.0
  2..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  BYE sip:1112@89.221.63.10:56340 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1542;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bKee28.20810
  b41.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK271944..To: <sip:1112@89.221.63.10>;tag=241CD07A-2596..From: <si
  p:4926@89.221.48.250>;tag=1542..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 438 BYE..Max-Forwards: 19..User-Agent: Express Talk 2.0
  2..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  BYE sip:1112@89.221.63.10:56340 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1542;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bKee28.20810
  b41.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK271944..To: <sip:1112@89.221.63.10>;tag=241CD07A-2596..From: <si
  p:4926@89.221.48.250>;tag=1542..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 438 BYE..Max-Forwards: 19..User-Agent: Express Talk 2.0
  2..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  BYE sip:1112@89.221.63.10:56340 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1542;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bKee28.20810
  b41.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK271944..To: <sip:1112@89.221.63.10>;tag=241CD07A-2596..From: <si
  p:4926@89.221.48.250>;tag=1542..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 438 BYE..Max-Forwards: 19..User-Agent: Express Talk 2.0
  2..Content-Length: 0....
#
U 89.221.48.250:5060 -> 89.221.63.10:56340
  BYE sip:1112@89.221.63.10:56340 SIP/2.0..Record-Route: <sip:89.221.48.250;lr;ftag=1542;nat=yes>..Via: SIP/2.0/UDP 89.221.48.250;branch=z9hG4bKee28.20810
  b41.0..Via: SIP/2.0/UDP 192.168.0.7:5070;received=89.221.63.16;rport=5070;branch=z9hG4bK271944..To: <sip:1112@89.221.63.10>;tag=241CD07A-2596..From: <si
  p:4926@89.221.48.250>;tag=1542..Call-ID: C17866D9-C5C111DD-8FEEFC21-97194A52@89.221.63.10..CSeq: 438 BYE..Max-Forwards: 19..User-Agent: Express Talk 2.0
  2..Content-Length: 0....

А впечатление, что циске что-то не нравится в BYE и она не относит его к текущему звонку? хотя Call-ID совпадает.

Никто с таким не сталкивался? Какие есть у кого идеи?
(трассировки сняты на участке <4>)