[Kamailio-Users] Problem with PRACK - sr-users

10 Jun 2009

Hi guys,

I'm facing an awkward issue with a Kamailio (1.4.3-notls (i386/linux))
regarding PRACK messages.

I'm migrating an old OpenSER (1.2.2-notls (i386/linux)) to this new Kamailio
that is connected to some customer GWs. The GWs we use are Huawei AR2810 and
Cisco AS5350.

Both GWs support 100rel and for some signalling they send PRACK messages
that are forwarded by OpenSER but consumed by Kamailio.
What I was able to troubleshoot shown that Kamailio is not recognizing the
lr=on on the header. I tested for PRACK messages within the following
segment:

# subsequent messages within a dialog should take the
# path determined by record-routing

if (is_method("PRACK"))
{
    xlog("L_ERR", "PRACK: Outside LR...\n");
};
if (loose_route())
{
    if (is_method("PRACK"))
    {
    xlog("L_ERR", "PRACK: Inside LR...\n");
    };
    # mark routing logic in request
    append_hf("P-hint: rr-enforced\r\n");
    route(1);
};

Did anyone have a similar issue with this version of Kamailio?

I captured the signalling for both proxies as follows:
KAMAILIO(192.168.200.130)
AS5350(192.168.200.40)
AR2810(192.168.216.4)
#
U 192.168.200.40:49395 -> 192.168.200.130:5060
  INVITE sip:3516380070@192.168.200.130:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK6107AA91..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;0>>;
  tag=D41203B4-1763..To:
<sip:3516380070@192.168.200.130<sip%3A3516380070@192.168.200.130>>..Date:
Wed, 10 Jun 2009 14:26:12 GMT..Call-ID:
7BE3750B-550111DE-86AD96C1-6209D7B9(a)192.168.200.4
  0..Supported: 100rel,timer,replaces..Min-SE:  1800..Cisco-Guid:
2078424251-1426133470-2747138075-1395155982..User-Agent:
Cisco-SIPGateway/IOS-12.x..Allo
  w: INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE,
NOTIFY, INFO, UPDATE, REGISTER..CSeq: 101 INVITE..Max-Forwards:
70..Remote-Party-I
  D: <sip:1143314808@192.168.200.40
<sip%3A1143314808@192.168.200.40>>;party=calling;screen=yes;privacy=off..Timestamp:
1244643972..Contact: <sip:1143314808@192.168.200.40:5060>..Expires:
  180..Allow-Events: telephone-event..Content-Type:
application/sdp..Content-Length: 302....v=0..o=CiscoSystemsSIP-GW-UserAgent
8434 7851 IN IP4 192.168.2
  00.40..s=SIP Call..c=IN IP4 192.168.200.40..t=0 0..m=audio 16836 RTP/AVP
18 8 100..c=IN IP4 192.168.200.40..a=rtpmap:18 G729/8000..a=fmtp:18
annexb=no..
  a=rtpmap:8 PCMA/8000..a=rtpmap:100 X-NSE/8000..a=fmtp:100
192-194..a=direction:passive..
#
U 192.168.200.130:5060 -> 192.168.216.4:5060
  INVITE sip:3516380070@192.168.216.4
<sip%3A3516380070@192.168.216.4>SIP/2.0..Record-Route:
<sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Via:
SIP/2.0/UDP 192.168.200.130;branch=z9hG4
  bKf574.3149a801.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK6107AA91..From:
<sip:1143314808@192.168.200.40
<sip%3A1143314808@192.168.200.40>>;tag=D41203B4-1763..To:
<sip:35163
  80070@192.168.200.130>..Date: Wed, 10 Jun 2009 14:26:12 GMT..Call-ID:
7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40..Supported:
100rel,timer,replac
  es..Min-SE:  1800..Cisco-Guid:
2078424251-1426133470-2747138075-1395155982..User-Agent:
Cisco-SIPGateway/IOS-12.x..Allow: INVITE, OPTIONS, BYE, CANCEL,
  ACK, PRACK, COMET, REFER, SUBSCRIBE, NOTIFY, INFO, UPDATE, REGISTER..CSeq:
101 INVITE..Max-Forwards: 69..Remote-Party-ID: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;
...
 ;party=calling;screen=yes;privacy=off..Timestamp:
1244643972..Contact: < sip:1143314808@192.168.200.40:5060>..Expires:
180..Allow-Events:
telephone-even
  t..Content-Type: application/sdp..Content-Length:
302....v=0..o=CiscoSystemsSIP-GW-UserAgent 8434 7851 IN IP4
192.168.200.40..s=SIP Call..c=IN IP4 192.1
  68.200.40..t=0 0..m=audio 16836 RTP/AVP 18 8 100..c=IN IP4
192.168.200.40..a=rtpmap:18 G729/8000..a=fmtp:18 annexb=no..a=rtpmap:8
PCMA/8000..a=rtpmap:10
  0 X-NSE/8000..a=fmtp:100 192-194..a=direction:passive..
#
U 192.168.200.130:5060 -> 192.168.200.40:5060
  SIP/2.0 100 Giving a try..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK6107AA91..From:
<sip:1143314808@192.168.200.40
<sip%3A1143314808@192.168.200.40>>;tag=D41203B4-1763..To:
<si
  p:3516380070@192.168.200.130 <p%3A3516380070@192.168.200.130>>..Call-ID:
7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40..CSeq: 101
INVITE..Server: Kamailio (1.4.3-notls (i386/linux)
  )..Content-Length: 0....
#
U 192.168.216.4:5060 -> 192.168.200.130:5060
  SIP/2.0 100
Trying..Call-ID:7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40..CSeq:101
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...
 ;tag=D41203B4-1763.  
.To:<sip:3516380070@192.168.200.130
<sip%3A3516380070@192.168.200.130>>..Via:SIP/2.0/UDP
192.168.200.130;branch=z9hG4bKf574.3149a801.0..Via:SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK6
  107AA91..Content-Length:0....
#
U 192.168.216.4:5060 -> 192.168.200.130:5060
  SIP/2.0 180
Ringing..Require:100rel..Supported:100rel..Record-Route:<sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Via:SIP/2.0/UDP
192.168.200.130;bran
  ch=z9hG4bKf574.3149a801.0..Via:SIP/2.0/UDP 192.168.200.40:5060
;branch=z9hG4bK6107AA91..Call-ID:7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40.
.CSeq:
  101
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...

;tag=D41203B4-1763..To:<sip:3516380070@192.168.200.130<sip%3A3516380070@192.168.200.130>
;tag=5358336B534F02B30582AFF0..RSeq:717562865..Co  
ntact:<sip:3516380070@192.168.200.130:5060>..Content-Length:0....
#
U 192.168.200.130:5060 -> 192.168.200.40:5060
  SIP/2.0 180
Ringing..Require:100rel..Supported:100rel..Record-Route:<sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Via:SIP/2.0/UDP
192.168.200.40:5060;

branch=z9hG4bK6107AA91..Call-ID:7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40..CSeq:101
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...
 ;tag=D41203B4-1  
763..To:<sip:3516380070@192.168.200.130 &lt;sip%3A3516380070(a)192.168.200.130&gt;
...

;tag=5358336B534F02B30582AFF0..RSeq:717562865..Contact:<
sip:3516380070@192.168.200.130:5060>..Content-Length:0..
  ..
#
U 192.168.200.40:49395 -> 192.168.200.130:5060
  PRACK sip:3516380070@192.168.200.130:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK6107D249F..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;0>>;
  tag=D41203B4-1763..To:
<sip:3516380070@192.168.200.130<sip%3A3516380070@192.168.200.130>>;tag=5358336B534F02B30582AFF0..Date:
Wed, 10 Jun 2009 14:26:12 GMT..Call-ID: 7BE3750B-550111DE-86
  AD96C1-6209D7B9@192.168.200.40..CSeq: 102 PRACK..RAck: 717562865 101
INVITE..Route: <sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Max-Forwards:
70..Co
  ntent-Length: 0....
#
U 192.168.216.4:5060 -> 192.168.200.130:5060
  SIP/2.0 180
Ringing..Require:100rel..Supported:100rel..Record-Route:<sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Via:SIP/2.0/UDP
192.168.200.130;bran
  ch=z9hG4bKf574.3149a801.0..Via:SIP/2.0/UDP 192.168.200.40:5060
;branch=z9hG4bK6107AA91..Call-ID:7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40.
.CSeq:
  101
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...

;tag=D41203B4-1763..To:<sip:3516380070@192.168.200.130<sip%3A3516380070@192.168.200.130>
;tag=5358336B534F02B30582AFF0..RSeq:717562865..Co  
ntact:<sip:3516380070@192.168.200.130:5060>..Content-Length:0....
#
U 192.168.200.130:5060 -> 192.168.200.40:5060
  SIP/2.0 180
Ringing..Require:100rel..Supported:100rel..Record-Route:<sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Via:SIP/2.0/UDP
192.168.200.40:5060;

branch=z9hG4bK6107AA91..Call-ID:7BE3750B-550111DE-86AD96C1-6209D7B9@192.168.200.40..CSeq:101
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...
 ;tag=D41203B4-1  
763..To:<sip:3516380070@192.168.200.130 &lt;sip%3A3516380070(a)192.168.200.130&gt;
...

;tag=5358336B534F02B30582AFF0..RSeq:717562865..Contact:<
sip:3516380070@192.168.200.130:5060>..Content-Length:0..
  ..
#
U 192.168.200.40:49395 -> 192.168.200.130:5060
  PRACK sip:3516380070@192.168.200.130:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK6107D249F..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;0>>;
  tag=D41203B4-1763..To:
<sip:3516380070@192.168.200.130<sip%3A3516380070@192.168.200.130>>;tag=5358336B534F02B30582AFF0..Date:
Wed, 10 Jun 2009 14:26:12 GMT..Call-ID: 7BE3750B-550111DE-86
  AD96C1-6209D7B9@192.168.200.40..CSeq: 102 PRACK..RAck: 717562865 101
INVITE..Route: <sip:192.168.200.130;lr=on;ftag=D41203B4-1763>..Max-Forwards:
70..Co
  ntent-Length: 0....

And then for OPENSER(192.168.200.10)
AS5350(192.168.200.40)
AR2810(192.168.216.4)
#
U 192.168.200.40:50112 -> 192.168.200.10:5060
  INVITE sip:3516380070@192.168.200.10:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D741D2C..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;0>>;
  tag=D3E4E024-AA5..To:
<sip:3516380070@192.168.200.10<sip%3A3516380070@192.168.200.10>>..Date:
Wed, 10 Jun 2009 13:36:54 GMT..Call-ID:
98989BF6-54FA11DE-818396C1-6209D7B9(a)192.168.200.40.
  .Supported: 100rel,timer,replaces..Min-SE:  1800..Cisco-Guid:
2560098254-1425674718-2728198171-1395155982..User-Agent:
Cisco-SIPGateway/IOS-12.x..Allow:
   INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE,
NOTIFY, INFO, UPDATE, REGISTER..CSeq: 101 INVITE..Max-Forwards:
70..Remote-Party-ID:
   <sip:1143314808@192.168.200.40
<sip%3A1143314808@192.168.200.40>>;party=calling;screen=yes;privacy=off..Timestamp:
1244641014..Contact: <sip:1143314808@192.168.200.40:5060>..Expires: 18
  0..Allow-Events: telephone-event..Content-Type:
application/sdp..Content-Length: 302....v=0..o=CiscoSystemsSIP-GW-UserAgent
2319 3741 IN IP4 192.168.200
  .40..s=SIP Call..c=IN IP4 192.168.200.40..t=0 0..m=audio 17416 RTP/AVP 18
8 100..c=IN IP4 192.168.200.40..a=rtpmap:18 G729/8000..a=fmtp:18
annexb=no..a=
  rtpmap:8 PCMA/8000..a=rtpmap:100 X-NSE/8000..a=fmtp:100
192-194..a=direction:passive..
#
U 192.168.200.10:5060 -> 192.168.200.40:5060
  SIP/2.0 407 Proxy Authentication Required..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D741D2C..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;;tag=D3E4
  E024-AA5..To:
<sip:3516380070@192.168.200.10<sip%3A3516380070@192.168.200.10>>;tag=329cfeaa6ded039da25ff8cbb8668bd2.941d..Call-ID:
98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..CS
  eq: 101 INVITE..Proxy-Authenticate: Digest realm="metrotel",
nonce="4a2fb81ca554f5ff9ab57d058348ca3a20e35893"..Server: OpenSER
(1.2.2-notls (i386/linux)
  )..Content-Length: 0....
#
U 192.168.200.40:5060 -> 192.168.200.10:5060
  ACK sip:3516380070@192.168.200.10:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D741D2C..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;;tag
  =D3E4E024-AA5..To:
<sip:3516380070@192.168.200.10<sip%3A3516380070@192.168.200.10>>;tag=329cfeaa6ded039da25ff8cbb8668bd2.941d..Date:
Wed, 10 Jun 2009 13:36:54 GMT..Call-ID: 98989BF6-54F
  A11DE-818396C1-6209D7B9@192.168.200.40..Max-Forwards: 70..CSeq: 101
ACK..Content-Length: 0....
#
U 192.168.200.40:50112 -> 192.168.200.10:5060
  INVITE sip:3516380070@192.168.200.10:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D751268..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;0>>;
  tag=D3E4E024-AA5..To:
<sip:3516380070@192.168.200.10<sip%3A3516380070@192.168.200.10>>..Date:
Wed, 10 Jun 2009 13:36:54 GMT..Call-ID:
98989BF6-54FA11DE-818396C1-6209D7B9(a)192.168.200.40.
  .Supported: 100rel,timer,replaces..Min-SE:  1800..Cisco-Guid:
2560098254-1425674718-2728198171-1395155982..User-Agent:
Cisco-SIPGateway/IOS-12.x..Allow:
   INVITE, OPTIONS, BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE,
NOTIFY, INFO, UPDATE, REGISTER..CSeq: 102 INVITE..Max-Forwards:
70..Remote-Party-ID:
   <sip:1143314808@192.168.200.40
<sip%3A1143314808@192.168.200.40>>;party=calling;screen=yes;privacy=off..Timestamp:
1244641014..Contact: <sip:1143314808@192.168.200.40:5060>..Expires: 18
  0..Allow-Events: telephone-event..Proxy-Authorization: Digest
username="as5350",realm="metrotel",uri="sip:3516380070@192.168.200.10:5060
",response="6a51

a32e9f21dadc67db011ab81af3f6",nonce="4a2fb81ca554f5ff9ab57d058348ca3a20e35893",algorithm=md5..Content-Type:
application/sdp..Content-Length: 302....v=0.
  .o=CiscoSystemsSIP-GW-UserAgent 2319 3741 IN IP4 192.168.200.40..s=SIP
Call..c=IN IP4 192.168.200.40..t=0 0..m=audio 17416 RTP/AVP 18 8 100..c=IN
IP4 19
  2.168.200.40..a=rtpmap:18 G729/8000..a=fmtp:18 annexb=no..a=rtpmap:8
PCMA/8000..a=rtpmap:100 X-NSE/8000..a=fmtp:100
192-194..a=direction:passive..
#
U 192.168.200.10:5060 -> 192.168.200.40:5060
  SIP/2.0 100 Giving a try..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D751268..From:
<sip:1143314808@192.168.200.40
<sip%3A1143314808@192.168.200.40>>;tag=D3E4E024-AA5..To:
<si
  p:3516380070@192.168.200.10 <p%3A3516380070@192.168.200.10>>..Call-ID:
98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..CSeq: 102
INVITE..Server: OpenSER (1.2.2-notls (i386/linux)).
  .Content-Length: 0....
#
U 192.168.200.10:5060 -> 192.168.216.4:5060
  INVITE sip:3516380070@192.168.216.4:5060;transport=udp
SIP/2.0..Record-Route: <sip:192.168.200.10;lr=on;ftag=D3E4E024-AA5>..Via:
SIP/2.0/UDP 192.168.200
  .10;branch=z9hG4bK831b.861b9286.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D751268..From:
<sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;
...
 ;tag=D3E4E024-AA5   ..To:
<sip:3516380070@192.168.200.10
<sip%3A3516380070@192.168.200.10>>..Date:
Wed, 10 Jun 2009 13:36:54 GMT..Call-ID:
98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..Supported: 100r
  el,timer,replaces..Min-SE:  1800..Cisco-Guid:
2560098254-1425674718-2728198171-1395155982..User-Agent:
Cisco-SIPGateway/IOS-12.x..Allow: INVITE, OPTIONS
  , BYE, CANCEL, ACK, PRACK, COMET, REFER, SUBSCRIBE, NOTIFY, INFO, UPDATE,
REGISTER..CSeq: 102 INVITE..Max-Forwards: 70..Remote-Party-ID:
<sip:1143314808
  @192.168.200.40>;party=calling;screen=yes;privacy=off..Timestamp:
1244641014..Contact: <sip:1143314808@192.168.200.40:5060>..Expires:
180..Allow-Events:
   telephone-event..Content-Type: application/sdp..Content-Length:
302..P-hint: outbound....v=0..o=CiscoSystemsSIP-GW-UserAgent 2319 3741 IN
IP4 192.168.2
  00.40..s=SIP Call..c=IN IP4 192.168.200.40..t=0 0..m=audio 17416 RTP/AVP
18 8 100..c=IN IP4 192.168.200.40..a=rtpmap:18 G729/8000..a=fmtp:18
annexb=no..
  a=rtpmap:8 PCMA/8000..a=rtpmap:100 X-NSE/8000..a=fmtp:100
192-194..a=direction:passive..
#
U 192.168.216.4:5060 -> 192.168.200.10:5060
  SIP/2.0 100
Trying..Call-ID:98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..CSeq:102
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...
 ;tag=D3E4E024-AA5..  
To:<sip:3516380070@192.168.200.10
<sip%3A3516380070@192.168.200.10>>..Via:SIP/2.0/UDP
192.168.200.10;branch=z9hG4bK831b.861b9286.0..Via:SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D7
  51268..Content-Length:0....
#
U 192.168.216.4:5060 -> 192.168.200.10:5060
  SIP/2.0 180
Ringing..Require:100rel..Supported:100rel..Record-Route:<sip:192.168.200.10;lr=on;ftag=D3E4E024-AA5>..Via:SIP/2.0/UDP
192.168.200.10;branch=
  z9hG4bK831b.861b9286.0..Via:SIP/2.0/UDP 192.168.200.40:5060
;branch=z9hG4bK60D751268..Call-ID:98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40.
.CSeq:10
  2 INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...

;tag=D3E4E024-AA5..To:<sip:3516380070@192.168.200.10<sip%3A3516380070@192.168.200.10>
;tag=5358336B534F54210582B350..RSeq:900097065..Contac  
t:<sip:3516380070@192.168.200.10:5060>..Content-Length:0....
#
U 192.168.200.10:5060 -> 192.168.200.40:5060
  SIP/2.0 180
Ringing..Require:100rel..Supported:100rel..Record-Route:<sip:192.168.200.10;lr=on;ftag=D3E4E024-AA5>..Via:SIP/2.0/UDP
192.168.200.40:5060;br

anch=z9hG4bK60D751268..Call-ID:98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..CSeq:102
INVITE..From:<sip:1143314808@192.168.200.40<sip%3A1143314808@192.168.200.40>
...
 ;tag=D3E4E024-AA  
5..To:<sip:3516380070@192.168.200.10 &lt;sip%3A3516380070(a)192.168.200.10&gt;
...

;tag=5358336B534F54210582B350..RSeq:900097065..Contact:<
sip:3516380070@192.168.200.10:5060>..Content-Length:0....
#
U 192.168.200.40:50112 -> 192.168.200.10:5060
  PRACK sip:3516380070@192.168.200.10:5060 SIP/2.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D77201C..From: <
sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;&gt;;t
  ag=D3E4E024-AA5..To:
<sip:3516380070@192.168.200.10<sip%3A3516380070@192.168.200.10>>;tag=5358336B534F54210582B350..Date:
Wed, 10 Jun 2009 13:36:54 GMT..Call-ID: 98989BF6-54FA11DE-81839
  6C1-6209D7B9@192.168.200.40..CSeq: 103 PRACK..RAck: 900097065 102
INVITE..Route:
<sip:192.168.200.10;lr=on;ftag=D3E4E024-AA5>..Proxy-Authorization: Dige
  st username="as5350",realm="metrotel",uri="
sip:3516380070@192.168.200.10:5060
",response="df4f26f89f7a4eebb397266d31e71b38",nonce="4a2fb81ca554f5ff9ab57d
  058348ca3a20e35893",algorithm=md5..Max-Forwards: 70..Content-Length: 0....
#
U 192.168.200.10:5060 -> 192.168.216.4:5060
  PRACK sip:3516380070@192.168.216.4:5060;transport=udp
SIP/2.0..Record-Route: <sip:192.168.200.10;lr=on;ftag=D3E4E024-AA5>..Via:
SIP/2.0/UDP 192.168.200.
  10;branch=z9hG4bK931b.4afe556.0..Via: SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D77201C..From:
<sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;
...
 ;tag=D3E4E024-AA5..   To:
<sip:3516380070@192.168.200.10
<sip%3A3516380070@192.168.200.10>>;tag=5358336B534F54210582B350..Date:
Wed, 10 Jun 2009 13:36:54 GMT..Call-ID:
98989BF6-54FA11DE-818396C1-6209D7B9@192.
  168.200.40..CSeq: 103 PRACK..RAck: 900097065 102
INVITE..Proxy-Authorization: Digest
username="as5350",realm="metrotel",uri="
sip:3516380070@192.168.200. &lt;sip%3A3516380070(a)192.168.200.&gt;

10:5060",response="df4f26f89f7a4eebb397266d31e71b38",nonce="4a2fb81ca554f5ff9ab57d058348ca3a20e35893",algorithm=md5..Max-Forwards:
70..Content-Length: 0
  ..P-hint: rr-enforced....
#
U 192.168.216.4:5060 -> 192.168.200.10:5060
  SIP/2.0 200
OK..Call-ID:98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..CSeq:103
PRACK..From:<sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;
...
 ;tag=D3E4E024-AA5..To:<s  
ip:3516380070@192.168.200.10
<ip%3A3516380070@192.168.200.10>>;tag=5358336B534F54210582B350..Via:SIP/2.0/UDP
192.168.200.10;branch=z9hG4bK931b.4afe556.0..Via:SIP/2.0/UDP 192.168.200.40:
  5060;branch=z9hG4bK60D77201C..Content-Length:0....
#
U 192.168.200.10:5060 -> 192.168.200.40:5060
  SIP/2.0 200
OK..Call-ID:98989BF6-54FA11DE-818396C1-6209D7B9@192.168.200.40..CSeq:103
PRACK..From:<sip:1143314808@192.168.200.40 &lt;sip%3A1143314808(a)192.168.200.40&gt;
...
 ;tag=D3E4E024-AA5..To:<s  
ip:3516380070@192.168.200.10
<ip%3A3516380070@192.168.200.10>>;tag=5358336B534F54210582B350..Via:SIP/2.0/UDP
192.168.200.40:5060;branch=z9hG4bK60D77201C..Content-Length:0....