We have WebRTC client behind load balancer. We make call to softphone from WebRTC, call from softphone is transferred to external number using Asterisk.

When call is hanged up on external number side, it doesn't hangs up on WebRTC client side.

If TOPOH is not enabled, this issue doesn't occur.

We have the following TOPOH-related sections of kamailio.cfg:

<...>

#!ifdef WITH_TOPOH

loadmodule "topoh.so"

#!endif

<...>

#!ifdef WITH_TOPOH

modparam("topoh", "mask_key", "xxxxxxxxxxxxxxxx")

modparam("topoh", "mask_ip", "10.0.0.1")

modparam("topoh", "mask_callid", 0)

modparam("topoh", "sanity_checks", 1)

modparam("topoh", "uparam_prefix", "")

modparam("topoh", "vparam_prefix", "")

modparam("topoh", "callid_prefix", "1337")

#!endif

<...>

#!ifdef WITH_DIALOG

modparam("dialog", "db_url", DBURL)

modparam("dialog", "db_mode", 1)

modparam("dialog", "db_fetch_rows", 800)

modparam("dialog", "track_cseq_updates", 1)

modparam("dialog", "ka_interval", 30)

modparam("dialog", "ka_timer", 30)

modparam("dialog", "send_bye", 0)

modparam("dialog", "dlg_filter_mode", 1)

#!ifdef WITH_TOPOH

modparam("dialog", "lreq_callee_headers", "TH: dlh\r\n")

#!endif

<...>

#!ifdef WITH_DISPATCHER

event_route[dispatcher:dst-up] {

sql_query("ds_dburl", "select description from dispatcher where destination='$ru'", "ds_dbresult");

xlog("L_WARN", "Destination up: $ru, found name: $dbr(ds_dbresult=>[0,0])\n");

prom_gauge_set("trunk_reachability", "1", "$ru", "$dbr(ds_dbresult=>[0,0])");

}

event_route[dispatcher:dst-down] {

sql_query("ds_dburl", "select description from dispatcher where destination='$ru'", "ds_dbresult");

xlog("L_WARN", "Destination down: $ru, found name: $dbr(ds_dbresult=>[0,0])\n");

prom_gauge_set("trunk_reachability", "0", "$ru", "$dbr(ds_dbresult=>[0,0])");

}

#!endif

#!ifdef WITH_TOPOH

event_route[topoh:msg-sending] {

if(is_reply() and $rs=="302") {

drop;

}

#!endif

(can provide the full config, if needed)

We are receiving the following errors:

On transfer:

https://pastebin.com/H3FQ4Kpj

On hangup from external number side:

https://pastebin.com/wgfRzGbd

On hangup from WebRTC client side:

https://pastebin.com/sE0yhBae

There are also differences in SIP traffic when TOPOH is disabled and when it is enabled. With TOPOH enabled, apparently, ACK from Asterisk is not reaching kamailio:

asterisk INVITE -> kamailio -> WebRTC

WebRTC 200 -> kamailio -> asterisk

asterisk ACK -> kamailio -> -> ->

(SIP flows attached - topoh_on.csv, topoh_off.csv)

kamailio -v
version: kamailio 5.6.1 (x86_64/linux)

flags: USE_TCP, USE_TLS, USE_SCTP, TLS_HOOKS, USE_RAW_SOCKS, DISABLE_NAGLE, USE_MCAST, DNS_IP_HACK, SHM_MMAP, PKG_MALLOC, Q_MALLOC, F_MALLOC, TLSF_MALLOC, DBG_SR_MEMORY, USE_FUTEX, FAST_LOCK-ADAPTIVE_WAIT, USE_DNS_CACHE, USE_DNS_FAILOVER, USE_NAPTR, USE_DST_BLOCKLIST, HAVE_RESOLV_RES, TLS_PTHREAD_MUTEX_SHARED

ADAPTIVE_WAIT_LOOPS 1024, MAX_RECV_BUFFER_SIZE 262144, MAX_URI_SIZE 1024, BUF_SIZE 65535, DEFAULT PKG_SIZE 8MB

poll method support: poll, epoll_lt, epoll_et, sigio_rt, select.

id: unknown

compiled on 09:11:15 Nov 15 2022 with gcc 9.3.0

We have dockerized kamailio running on Ubuntu 16.04.3 LTS
Docker version 18.03.1-ce, build 9ee9f40

Please advise where to start looking.