[Linphone-developers] Linphonecsh Not Sending ACK to Cisco 200 OK[nophi]

[Ham, Ted]

Hello. Just want to say Linphonecsh is exactly what I needed, a SIP phone that 
can be dialed from within a PHP script. Having a problem with it though and I 
read all about my problem and none of the things to check pertain to my issue.

I loaded the Linphonecsh within the last week. This is just the command line 
version I loaded, not the full GUI one. I do not know how to look up what 
version of Linphonecsh I have, documentation on Linphonecsh is nowhere to 
really be found except for the 5 or so simple command line commands. I do not 
know if it even keeps logs or where its installed. I really wish there was more 
developer documentation on the Linphoncsh app. It is on my Ubuntu 18.04 Linux 
box. I only use this Linux box for Linphonecsh, brand new install, that's it. 
Since it's in my lab, there is absolutely NO security or firewalls on anything.

This Linux box has only 1 NIC in it is running Linphonecsh is directly 
connected to my Cisco 2921 router on a /24 subnet, running Call manager Express 
(which is NOT connected to the outside world at all). It is in my lab, on the 
same subnet. This is such a simple setup that you can't suggest any of the 
normal things that might mess up the phone call. There are no other IP 
addresses involved. There is no NAT, no firewall, no routing, no ACL's, no 
nothing that would either change, manipulate, block or mess up the IP/port 
connectivity between the Linphonecsh and the Cisco router.

I can dial the Linphonecsh by command line to call a Cisco phone extension on 
my Call manager Express (CME). The Cisco phone rings, I answer the call and the 
call only stays up for 9 seconds. SIP traces and Wireshark says the Cisco is 
sending 200 ok's after the call is up but the Linphonecsh never sends any 
ACK's, thus the call drops. The SIP headers have the proper IP's in place in 
the TO and FROM and CONTACT headers.  I do not need any voice to work on this 
Linphonecsh phone call, I am just using it to call the Cisco and I need that 
call to stay active until the Linphonecsh hangs up. Since the Linphonecsh never 
sands any ACK's to the Cisco, the Cisco sends a BYE to the Linphonecsh and the 
Linphonecsh responds to the Cisco with an OK, so I know the Linphonecsh 
communicates. The Linphonecsh will not send that ACK. Why not?

I have read all the normal things that people say to check but my setup is 
perfect, stripped down and nothing, and I really mean nothing is in the way to 
interfere with the Linphonecsh either properly receiving the 200 ok's or the 
Linphonecsh to send the ACK. Wireshark is in the middle of the 5 foot CAT-5 
that links the two so I know the 200 ok's are getting to the Linphonecsh.

Also, the Linphonecsh unregister and exit commands DO NOT work after the phone 
call is through. I have to issue the command, killall -9 linphonec to manually 
kill the session so as to dial another phone number. I can deal with this as I 
made a script to do the killing.

Any suggestions? Linphonecsh is such a simple app I do not know why it just 
doesn't function like it should.

Thank you kindly,

Ted

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