expected behavior of TCP keepalive about re HOT 3 CLOSED

Can you try to add a debug msg to the keepalive handler:

--- a/src/sip/transp.c
+++ b/src/sip/transp.c
@@ -316,6 +316,8 @@ static void conn_keepalive_handler(void *arg)
        mb.pos  = 0;
        mb.end  = 4;
 
+       DEBUG_WARNING("KEEPALIVE\n");
+
        err = tcp_send(conn->tc, &mb);
        if (err) {
                conn_close(conn, err);

You can do the same for sip_keepalive_tcp to see if the timer handler setup is working.

from re.

in general it is probably better to use the mailing list for questions like this.

I think the sip outbound ping/pong feature is only enabled if supported by the SIP Server.
Please check in the source code.

You can also use a low registration interval to keep the TCP connection open:

;regint=60

please note that some networks (CGN) will kill random TCP connections at random times.
If you want this to work reliably you need to re-connection TCP from the client side.

from re.

Agreed, thanks for the support; I'll let you know if we will detect anything meaningful.

from re.