Hello,

I've already suppressed this via routing logic, however I was wondering if there is a dedicated parameter that handles this. I'm currently running version 5.6.4.

Scenario:
UA-1 registered towards kamailio, calls UA-2 which is registered towards a different platform (non kamailio); so there are 2 proxys involved. kamailio is set to fork the call to voicemail if there is either no response completely from the other end, or the call goes unanswered.

So the initial leg is:

UA-1 <-----> kamailio <-----> second proxy <-----> UA-2

Issue:
I'm trying to catch a case where the second proxy does issue a "100 Trying" for the initial INVITE; and then timesout. The call does fork to voicemail; however 14000+ SIP packets are generated between kamailio and the second proxy of CANCEL and "100 Trying" (the 100 Trying has a CSeq for INVITE still).

Is there a way to suppress the amount of CANCELs that is transmitted in this situation?

I'm using the following as my "tm" parameters:
modparam("tm", "failure_reply_mode", 3)
modparam("tm", "fr_timer", 30000)
modparam("tm", "fr_inv_timer", 300000)
modparam("tm", "auto_inv_100_reason", "Trying")

Thanks.

Example SIP trace:
(UA-1 --> kamailio)
72.255.255.255 --> 10.64.52.110

INVITE sip:131@sip-example.com SIP/2.0
v: SIP/2.0/UDP 10.0.0.102:51519;branch=z9hG4bK-xfelmyyjzne5;rport
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
Max-Forwards: 70
User-Agent: snomD785/10.1.152.12
m: <sip:133@10.0.0.102:51519;line=6dv00d6r>;reg-id=1
Accept: application/sdp
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO, UPDATE
Allow-Events: talk, hold, refer, call-info
Supported: timer, replaces, from-change
Session-Expires: 3600
Min-SE: 90
Proxy-Authorization: Digest username="133",realm="sip-example.com",nonce="ZOTEBGTkwtiM22ZE8IJsn/esiW3CZrt0",uri="sip:131@sip-example.com",response="fb44b4fe0f8fb17de13f043cf1248e14",algorithm=MD5
c: application/sdp
l: 309

v=0
o=root 481174289 481174289 IN IP4 10.0.0.102
s=call
c=IN IP4 10.0.0.102
t=0 0
m=audio 50864 RTP/AVP 9 0 8 18 101
a=rtpmap:9 G722/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=sendrecv

--------------------------------------------
(UA-1 <-- kamailio)
72.255.255.255 <-- 10.64.52.110

SIP/2.0 100 Trying
v: SIP/2.0/UDP 10.0.0.102:51519;branch=z9hG4bK-xfelmyyjzne5;rport=51519;received=72.255.255.255
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
Content-Length: 0

--------------------------------------------
(kamailio --> second proxy)
10.64.52.110 --> 10.64.52.100

INVITE sip:second-proxy-example.com:5066;ua=43a58ecca39c9c8f37515e55b5b37ed7 SIP/2.0
Via: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.0
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com?vm-ext%3D100%26ext-to%3D131%26ext-from%3D133>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
Max-Forwards: 15
Accept: application/sdp
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO, UPDATE
Allow-Events: talk, hold, refer, call-info
Supported: timer, replaces, from-change
Session-Expires: 3600
Min-SE: 90
c: application/sdp
l: 313
Contact: <sip:leg_1@sip-example.com;ccr=btpsh-64e387e0-ee528-2>

v=0
o=root 481174289 481174289 IN IP4 10.64.52.111
s=call
c=IN IP4 10.64.52.111
t=0 0
m=audio 34084 RTP/AVP 9 0 8 18 101
a=rtpmap:9 G722/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=sendrecv

--------------------------------------------
(kamailio <-- second proxy)
10.64.52.110 <-- 10.64.52.100

SIP/2.0 100 Trying
v: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.0
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com?vm-ext%3D100%26ext-to%3D131%26ext-from%3D133>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
l: 0


--------------------------------------------
After 10 seconds of no further response from second proxy, call is forked to voicemail
(kamailio --> voicemail)
10.64.52.110 --> 10.64.56.10

INVITE sip:voicemail@voicemail-example.com SIP/2.0
Via: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.1
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com?vm-ext%3D100%26ext-to%3D131%26ext-from%3D133>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
Max-Forwards: 15
Accept: application/sdp
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO, UPDATE
Allow-Events: talk, hold, refer, call-info
Supported: timer, replaces, from-change
Session-Expires: 3600
Min-SE: 90
c: application/sdp
l: 313
Contact: <sip:leg_1@sip-example.com;ccr=btpsh-64e387e0-ee533-3>

v=0
o=root 481174289 481174289 IN IP4 10.64.52.111
s=call
c=IN IP4 10.64.52.111
t=0 0
m=audio 38722 RTP/AVP 9 0 8 18 101
a=rtpmap:9 G722/8000
a=rtpmap:0 PCMU/8000
a=rtpmap:8 PCMA/8000
a=rtpmap:18 G729/8000
a=fmtp:18 annexb=no
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=sendrecv

--------------------------------------------
At roughly the same time, CANCEL is issued towards the second proxy
(kamailio --> second proxy)
10.64.52.110 --> 10.64.52.100

CANCEL sip:second-proxy-example.com:5066;ua=43a58ecca39c9c8f37515e55b5b37ed7 SIP/2.0
Via: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.0
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 CANCEL
Max-Forwards: 15
l: 0

--------------------------------------------
(kamailio <-- voicemail)
10.64.52.110 <-- 10.64.56.10

SIP/2.0 200 Ok
Via: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.1
From: <sip:133@sip-example.com>;tag=i4mlq4jr0y
To: <sip:131@sip-example.com?vm-ext%3D100%26ext-to%3D131%26ext-from%3D133>;tag=vzx5x3mlbd
Call-ID: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
Contact: <sip:voicemail@10.64.56.10:5078>
Require: timer
Session-Expires: 3600;refresher=uac
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO
Supported: timer, 100rel, replaces
Content-Type: application/sdp
Content-Length: 264

v=0
o=root 1084843702 1084843703 IN IP4 10.64.56.10
s=call
c=IN IP4 10.64.56.10
t=0 0
m=audio 31908 RTP/AVP 0 101
a=rtpmap:0 pcmu/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=alt:1 0.9 : user 9kksj== 10.64.56.10 31908
a=sendrecv

--------------------------------------------
(UA-1 <-- kamailio)
72.255.255.255 <-- 10.64.52.110

SIP/2.0 200 Ok
From: <sip:133@sip-example.com>;tag=i4mlq4jr0y
To: <sip:131@sip-example.com?vm-ext%3D100%26ext-to%3D131%26ext-from%3D133>;tag=vzx5x3mlbd
Call-ID: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
Require: timer
Session-Expires: 3600;refresher=uac
Allow: INVITE, ACK, CANCEL, BYE, REFER, OPTIONS, NOTIFY, SUBSCRIBE, PRACK, MESSAGE, INFO
Supported: timer, 100rel, replaces
Content-Type: application/sdp
Content-Length: 270
Via: SIP/2.0/UDP 10.0.0.102:51519;received=72.255.255.255;branch=z9hG4bK-xfelmyyjzne5;rport=51519
Contact: <sip:leg_2@sip-example.com;ccr=atpsh-64e387e0-ee533-3>

v=0
o=root 1084843702 1084843703 IN IP4 10.64.52.110
s=call
c=IN IP4 10.64.52.110
t=0 0
m=audio 33552 RTP/AVP 0 101
a=rtpmap:0 pcmu/8000
a=rtpmap:101 telephone-event/8000
a=fmtp:101 0-15
a=ptime:20
a=alt:1 0.9 : user 9kksj== 10.64.56.10 31908
a=sendrecv


===============================================
These next 2 SIP packets repeat, generating 14000+ CANCEL <--> 100 Trying transactions between kamailio, and the second proxy.
(kamailio --> second proxy)
10.64.52.110 --> 10.64.52.100

CANCEL sip:second-proxy-example.com:5066;ua=43a58ecca39c9c8f37515e55b5b37ed7 SIP/2.0
Via: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.0
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 CANCEL
Max-Forwards: 15
l: 0

--------------------------------------------
(kamailio <-- second proxy)
10.64.52.110 <-- 10.64.52.100

SIP/2.0 100 Trying
v: SIP/2.0/UDP 10.64.52.110:5060;branch=z9hG4bKecf9.6d10880e1353b8a7bbf0383d934a38a5.0
f: <sip:133@sip-example.com>;tag=i4mlq4jr0y
t: <sip:131@sip-example.com?vm-ext%3D100%26ext-to%3D131%26ext-from%3D133>
i: 95c3e4642670-rx28v46dte4p
CSeq: 1 INVITE
l: 0