[Spce-user] Missing ACK after T.38 re-INVITE from provider

Thu Mar 7 12:16:16 EST 2019

Hello Everyone,

I'm having an issue with sending faxes using T.38 (receiving works fine)
when the provider sends the re-INVITE.  This is with SPCE 6.5.3, and the
problem is that after sending the 200 OK for the re-INVITE, we never get an
ACK back.  After looking at packet captures and working with the provider,
we think it has to do with the record-route headers.  The provider says we
shouldn't send them at all, but I think they might just be reversed.  Could
someone please take a look at the attached exchange and let me know if the
record-route headers in the 200 OK after re-INVITE look correct?  It seems
to me that they are reversed, since in the original INVITE and ACK they are
in opposite order, so I'm thinking they can't route the ACK back to us.
Then our SPCE keeps resending the 200 OK, and eventually the call hangs
up.  If there's a better way to send the trace let me know!

If I make the provider not send the re-INVITE, and our end sends it
instead, the call works fine.  I've also tried using "topos" to hide the
record-route headers, but in that case SPCE sends ACKs from the wrong
interface so it doesn't work either (probably separate problem).

Thanks,
Nate Baker
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.sipwise.com/mailman/private/spce-user_lists.sipwise.com/attachments/20190307/a51c2028/attachment.html>
-------------- next part --------------
------------------------SIP---------------------
INVITE sip:1888XXXXXXX at sip.provider.com SIP/2.0
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Via: SIP/2.0/UDP 50.xx.xx.xx;branch=z9hG4bK9085.8f22cae91e5c4727af2f763a55aff5c8.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKU~5PIaV2;rport=5080
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>
CSeq: 10 INVITE
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
Max-Forwards: 69
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, UPDATE, NOTIFY
Supported: path, replaces
P-Asserted-Identity: <sip:1877XXXXXXX at 192.168.2.151>
Content-Type: application/sdp
Content-Length: 290
Contact: <sip:ngcp-lb at 50.xx.xx.xx:5060;ngcpct=7369703a3132372e302e302e313a35303830>

v=0
o=FreeSWITCH 1551786545 1551786546 IN IP4 50.xx.xx.xx
s=FreeSWITCH
c=IN IP4 50.xx.xx.xx
t=0 0
m=audio 30362 RTP/AVP 0 101 13
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=rtpmap:13 CN/8000
a=sendrecv
a=rtcp:30363
a=ptime:20
a=direction:both

------------------------SIP---------------------
SIP/2.0 100 Provider trying
Via: SIP/2.0/UDP 50.xx.xx.xx;branch=z9hG4bK9085.8f22cae91e5c4727af2f763a55aff5c8.0;rport=5060
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKU~5PIaV2;rport=5080
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>
CSeq: 10 INVITE
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
Server: kamailio (5.0.7 (x86_64/linux))
Content-Length: 0

------------------------SIP---------------------
SIP/2.0 180 Ringing
Via: SIP/2.0/UDP 50.xx.xx.xx;rport=5060;branch=z9hG4bK9085.8f22cae91e5c4727af2f763a55aff5c8.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKU~5PIaV2;rport=5080
Record-Route: <sip:10.255.0.1;transport=tcp;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Record-Route: <sip:19.xx.xx.xx;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 10 INVITE
Contact: <sip:1888XXXXXXX at 10.15.10.4:5070;transport=tcp>
Accept: application/sdp
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, NOTIFY
Supported: path, replaces
Allow-Events: talk, hold, conference, refer
Content-Length: 0

------------------------SIP---------------------
SIP/2.0 183 Session Progress
Via: SIP/2.0/UDP 50.xx.xx.xx;rport=5060;branch=z9hG4bK9085.8f22cae91e5c4727af2f763a55aff5c8.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKU~5PIaV2;rport=5080
Record-Route: <sip:10.255.0.1;transport=tcp;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Record-Route: <sip:19.xx.xx.xx;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 10 INVITE
Contact: <sip:1888XXXXXXX at 10.15.10.4:5070;transport=tcp>
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, NOTIFY
Supported: path, replaces
Allow-Events: talk, hold, conference, refer
Content-Type: application/sdp
Content-Disposition: session
Content-Length: 291

v=0
o=FreeSWITCH 1551799454 1551799455 IN IP4 6.xx.xx.xx
s=FreeSWITCH
c=IN IP4 6.xx.xx.xx
t=0 0
m=audio 17752 RTP/AVP 0 101 13
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=rtpmap:13 CN/8000
a=ptime:20
a=mid:audio
a=rtcp:17753 IN IP4 6.xx.xx.xx

------------------------SIP---------------------
SIP/2.0 200 OK
Via: SIP/2.0/UDP 50.xx.xx.xx;rport=5060;branch=z9hG4bK9085.8f22cae91e5c4727af2f763a55aff5c8.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKU~5PIaV2;rport=5080
Record-Route: <sip:10.255.0.1;transport=tcp;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Record-Route: <sip:19.xx.xx.xx;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 10 INVITE
Contact: <sip:1888XXXXXXX at 10.15.10.4:5070;transport=tcp>
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, NOTIFY
Supported: path, replaces
Allow-Events: talk, hold, conference, refer
Content-Type: application/sdp
Content-Disposition: session
Content-Length: 291

v=0
o=FreeSWITCH 1551799454 1551799455 IN IP4 6.xx.xx.xx
s=FreeSWITCH
c=IN IP4 6.xx.xx.xx
t=0 0
m=audio 17752 RTP/AVP 0 101 13
a=rtpmap:0 PCMU/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-16
a=rtpmap:13 CN/8000
a=ptime:20
a=mid:audio
a=rtcp:17753 IN IP4 6.xx.xx.xx

------------------------SIP---------------------
ACK sip:1888XXXXXXX at 10.15.10.4:5070;transport=tcp SIP/2.0
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Via: SIP/2.0/UDP 50.xx.xx.xx;branch=z9hG4bK9085.261a3fc636b230ecb02a75dd162af36c.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKKS47Ua0I;rport=5080
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
CSeq: 10 ACK
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
Route: <sip:19.xx.xx.xx;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>, <sip:10.255.0.1;transport=tcp;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Max-Forwards: 69
Content-Length: 0
Contact: <sip:ngcp-lb at 50.xx.xx.xx:5060;ngcpct=7369703a3132372e302e302e313a35303830>

------------------------SIP---------------------
INVITE sip:ngcp-lb at 50.xx.xx.xx:5060;ngcpct=7369703a3132372e302e302e313a35303830 SIP/2.0
Via: SIP/2.0/UDP 19.xx.xx.xx;branch=z9hG4bK6315.eba789fb4dfcf6e7dc30309425fcd65d.0;i=c7659
Via: SIP/2.0/TCP 10.15.10.4:5070;received=10.15.10.4;rport=49001;branch=z9hG4bKr95j64Sy4a98j
Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Max-Forwards: 67
From: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
To: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 1354812 INVITE
Contact: <sip:1888XXXXXXX at 10.15.10.4:5070;transport=tcp>
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, NOTIFY
Supported: path, replaces
Content-Type: application/sdp
Content-Length: 316

v=0
o=FreeSWITCH 1551799454 1551799457 IN IP4 6.xx.xx.xx
s=FreeSWITCH
c=IN IP4 6.xx.xx.xx
t=0 0
m=image 17752 udptl t38
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:2000
a=T38FaxMaxDatagram:400
a=T38FaxUdpEC:t38UDPRedundancy

------------------------SIP---------------------
SIP/2.0 100 Trying
Via: SIP/2.0/UDP 19.xx.xx.xx;branch=z9hG4bK6315.eba789fb4dfcf6e7dc30309425fcd65d.0;i=c7659;rport=5060
Via: SIP/2.0/TCP 10.15.10.4:5070;received=10.15.10.4;rport=49001;branch=z9hG4bKr95j64Sy4a98j
From: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
To: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 1354812 INVITE
Server: Sipwise NGCP LB 6.X
Content-Length: 0

------------------------SIP---------------------
SIP/2.0 200 OK
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=tBeK36g09mmFm;ngcplb=yes;nat=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=tBeK36g09mmFm;ngcplb=yes;nat=yes;socket=udp:50.xx.xx.xx:5060>
Via: SIP/2.0/UDP 19.xx.xx.xx;rport=5060;branch=z9hG4bK6315.eba789fb4dfcf6e7dc30309425fcd65d.0;i=c7659
Via: SIP/2.0/TCP 10.15.10.4:5070;received=10.15.10.4;rport=49001;branch=z9hG4bKr95j64Sy4a98j
From: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
To: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 1354812 INVITE
Accept: application/sdp
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, UPDATE, NOTIFY
Supported: path, replaces
Content-Type: application/sdp
Content-Length: 360
Contact: <sip:ngcp-lb at 50.xx.xx.xx:5060;ngcpct=7369703a3132372e302e302e313a35303830>

v=0
o=FreeSWITCH 1551786545 1551786547 IN IP4 50.xx.xx.xx
s=FreeSWITCH
c=IN IP4 50.xx.xx.xx
t=0 0
m=image 30362 udptl t38
a=sendrecv
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:2000
a=T38FaxMaxDatagram:400
a=T38FaxUdpEC:t38UDPRedundancy
a=ptime:20
a=direction:both

------------------------SIP---------------------
SIP/2.0 200 OK
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=tBeK36g09mmFm;ngcplb=yes;nat=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=tBeK36g09mmFm;ngcplb=yes;nat=yes;socket=udp:50.xx.xx.xx:5060>
Via: SIP/2.0/UDP 19.xx.xx.xx;rport=5060;branch=z9hG4bK6315.eba789fb4dfcf6e7dc30309425fcd65d.0;i=c7659
Via: SIP/2.0/TCP 10.15.10.4:5070;received=10.15.10.4;rport=49001;branch=z9hG4bKr95j64Sy4a98j
From: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
To: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 1354812 INVITE
Accept: application/sdp
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, UPDATE, NOTIFY
Supported: path, replaces
Content-Type: application/sdp
Content-Length: 360
Contact: <sip:ngcp-lb at 50.xx.xx.xx:5060;ngcpct=7369703a3132372e302e302e313a35303830>

v=0
o=FreeSWITCH 1551786545 1551786547 IN IP4 50.xx.xx.xx
s=FreeSWITCH
c=IN IP4 50.xx.xx.xx
t=0 0
m=image 30362 udptl t38
a=sendrecv
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:2000
a=T38FaxMaxDatagram:400
a=T38FaxUdpEC:t38UDPRedundancy
a=ptime:20
a=direction:both

------------------------SIP---------------------
SIP/2.0 200 OK
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=tBeK36g09mmFm;ngcplb=yes;nat=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=tBeK36g09mmFm;ngcplb=yes;nat=yes;socket=udp:50.xx.xx.xx:5060>
Via: SIP/2.0/UDP 19.xx.xx.xx;rport=5060;branch=z9hG4bK6315.eba789fb4dfcf6e7dc30309425fcd65d.0;i=c7659
Via: SIP/2.0/TCP 10.15.10.4:5070;received=10.15.10.4;rport=49001;branch=z9hG4bKr95j64Sy4a98j
From: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
To: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 1354812 INVITE
Accept: application/sdp
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, UPDATE, NOTIFY
Supported: path, replaces
Content-Type: application/sdp
Content-Length: 360
Contact: <sip:ngcp-lb at 50.xx.xx.xx:5060;ngcpct=7369703a3132372e302e302e313a35303830>

v=0
o=FreeSWITCH 1551786545 1551786547 IN IP4 50.xx.xx.xx
s=FreeSWITCH
c=IN IP4 50.xx.xx.xx
t=0 0
m=image 30362 udptl t38
a=sendrecv
a=T38FaxVersion:0
a=T38MaxBitRate:14400
a=T38FaxFillBitRemoval
a=T38FaxRateManagement:transferredTCF
a=T38FaxMaxBuffer:2000
a=T38FaxMaxDatagram:400
a=T38FaxUdpEC:t38UDPRedundancy
a=ptime:20
a=direction:both

------------------------SIP---------------------
BYE sip:1888XXXXXXX at 10.15.10.4:5070;transport=tcp SIP/2.0
Record-Route: <sip:50.xx.xx.xx;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Record-Route: <sip:127.0.0.1;r2=on;lr=on;ftag=7537DC00-5C7ED9F500055D66-534EA700;ngcplb=yes;socket=udp:50.xx.xx.xx:5060>
Via: SIP/2.0/UDP 50.xx.xx.xx;branch=z9hG4bKa085.6880ec15728cff4fed449e40c0fb4340.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKHS8kBaa1;rport=5080
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
CSeq: 11 BYE
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
Route: <sip:19.xx.xx.xx;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>, <sip:10.255.0.1;transport=tcp;r2=on;lr;ftag=7537DC00-5C7ED9F500055D66-534EA700>
Max-Forwards: 69
User-Agent: Sipwise NGCP Application Server 6.X
Content-Length: 0

------------------------SIP---------------------
SIP/2.0 200 OK
Via: SIP/2.0/UDP 50.xx.xx.xx;rport=5060;branch=z9hG4bKa085.6880ec15728cff4fed449e40c0fb4340.0
Via: SIP/2.0/UDP 127.0.0.1:5080;received=127.0.0.1;branch=z9hG4bKHS8kBaa1;rport=5080
From: <sip:1877XXXXXXX at 192.168.2.151>;tag=7537DC00-5C7ED9F500055D66-534EA700
To: <sip:1888XXXXXXX at sip.provider.com>;tag=tBeK36g09mmFm
Call-ID: e7ac30e6-ba26-1237-2cad-005056a36f0d_b2b-1
CSeq: 11 BYE
Allow: INVITE, ACK, BYE, CANCEL, OPTIONS, MESSAGE, INFO, UPDATE, NOTIFY
Supported: path, replaces
Content-Length: 0