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#### Description

Based on the email thread : ``` [SR-Users] Dialog - timeout for dlg with CallIDInbox ``` Several users are facing unpexected dialog disconnection caused by no-ack timer.

Using a modified version of the dialog module to improve debug-ability ttps://github.com/kamailio/kamailio/pull/2483

I was able to confirm at least one problem and after looking at the trace, it seems like dialog mismatch with a serial forking scenario :

- log line 3 is telling us that a NO-ACK disconnection should be triggered - log line 1-2 is telling us what happened when the ACK was received in dlg_onroute(), oddly enough state 5 was old and new, could it be a mismatch/confusio with the previous dialog, looking in this direction ... ``` 1: 2020-09-25T16:30:16.896: dialog [dlg_handlers.c:1273]: extra_ack_debug_info(): [ACK][1] state not changed >>> call-id[562419_125824138_2072238224] to-tag[<sip:+14019991904@anon.com>;tag=gK02b68836] 2: 2020-09-25T16:30:16.896: dialog [dlg_handlers.c:1440]: dlg_onroute(): [ACK] state not changed old[5]new[5] ... 3: 2020-09-25T16:32:22.674: dialog [dlg_hash.c:247]: dlg_clean_run(): dialog disconnection no-ACK call-id[562419_125824138_2072238224][1601051416]<[1601051542 - 60] ```

After looking at the pcap trace, call-id 562419_125824138_2072238224 was involved in serial forking :

call attempt1 ``` X >> INVITE >> Y // no to-tag X << 100 ... X << 408 // to-tag=594d50c3218065a60bb91fd47a70fbc1-59edef02 (locally generated) X >> ACK // to-tag=594d50c3218065a60bb91fd47a70fbc1-59edef02 ``` call attempt2 ``` X >> INVITE >> Z // no to-tag X << 100 X << 200 << Z // to-tag=gK02b68836 X >> ACK >> Z // to-tag=gK02b68836 (Should be state old[3]new[4], I wonder how it could possibly be state old[5]new[5]) ```

I did look at several occurrences and there is always a locally generated 408/to-tag before, seems like I have a good lead to investigate further. You can view, comment on, or merge this pull request online at:

https://github.com/kamailio/kamailio/pull/2484

-- Commit Summary --

* dialog: dlg_cell, always check for a to-tag match

-- File Changes --

M src/modules/dialog/dlg_hash.c (13)

-- Patch Links --

https://github.com/kamailio/kamailio/pull/2484.patch https://github.com/kamailio/kamailio/pull/2484.diff