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Summary:ASTERISK-21955: [patch] Asterisk responds 488 to session timers re-Invite in an active T.38 dialog after exactly 5 seconds
Reporter:i2045 (i2045)Labels:patch
Date Opened:2013-06-25 09:26:35Date Closed:
Priority:MajorRegression?
Status:Open/NewComponents:Channels/chan_sip/T.38
Versions:1.8.22.0 13.18.4 Frequency of
Occurrence		Constant
Related
Issues:
is related toASTERISK-15596 T.38 session fails with '488 Not acceptable here' if within 5 seconds there is no "SIP 100 Trying" REINVITE reply from remote
Environment:Attachments:( 0) Asterisk_1.8.22.0_T.38_488_sip-conf_relevant.txt
( 1) Asterisk_1.8.22.0_T.38_488.txt
( 2) t38_session_timer.patch
Description:192.168.5.1 LAN IP address of client A
44.55.66.77 WAN IP address of client A
11.22.33.44 SIP proxy server
88.99.11.22 Asterisk 1.8.22.0 server
33.55.77.99 SIP server of client B
22.44.66.88 Media gateway of client B

- A call (G.711 alaw) is initiated by client A to client B.
- Client A re-Invites to T.38, Asterisk relays this re-Invite, client B accepts.
- Client B re-Invites (line #502). The only difference with the 200 OK that client B sent earlier (line #404) is the Session-Expires header. Asterisk responds immediately with "100 Trying" and "488 Not acceptable here" after exactly 5 seconds.
- The call is then re-Invited back to G.711 alaw and the fax fails.

Seems a similar problem as reported in 2010:
https://issues.asterisk.org/jira/browse/ASTERISK-15596?focusedCommentId=162618&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel#comment-162618

Does someone know why the second re-Invite is answered with a 488?
Comments:By: Matt Jordan (mjordan) 2013-07-07 18:26:44.060-0500

This looks to be a bug in the T.38 state machine in {{chan_sip}}. Due to the state it's in, it doesn't expect another re-INVITE when the remote session timer fires and so it rejects it with a 488 (which is typically the default "nope, I don't want this" that {{chan_sip}} responds with in the T.38 state machine).
By: Torrey Searle (tsearle) 2015-06-16 07:35:51.715-0500

this bug also exists in asterisk 11...
By: Torrey Searle (tsearle) 2015-06-17 10:02:37.013-0500

here is a patch fix this issue in asterisk 11
By: Rusty Newton (rnewton) 2015-06-25 08:20:05.743-0500

Torrey do you want to put that patch on Gerrit? Maybe it will simply work in 13 as well, and if not maybe someone else will port it once it is on there.