Voice fades on external call from MyTW

[alex]

Hi folks
OXE R8.0, MyTW - 7.1.4b4322.
When user calls from MyTW, e.g., any external party then after some seconds (can be 7, 10 or 25 seconds) the voice of called party "fades" and in a few moments completely disappears.
In opposite direction everything is OK.
The point is that due to some reasons MyTW server was moved to "public" Internet from private LAN. Before that it was OK.
It is clear that the problem is with RTP flow but why it starts working and then voice in one direction disappears?!
SIP traces and public trunk traces show nothing at the time when voice starts to fade.

Any idea appreciated from you.

[cavagnaro]

OXE communication to TW is made how? Another VLAN or has to route the call now to an internet domain?

[alex]

OXE communication to TW is made how? Another VLAN or has to route the call now to an internet domain?

Hi cav.
OXE connected via SIP TG.
At least on CS and GD no VLAN is used. May be they have port-based VLAN, I do not know.
Also in MyTW they do not have G.729 licenses. So all calls are in G.711A, so I think that's the problem, some switches/routers jamming or something.

Just looking for a way to see RTP flow on GD because wireshark does not handle properly SIP calls from MyTW to PSTN via OXE.

[Mr T]

So you have a firewall between OXE and Teamwork? I would test with another SIP device on public side to OXE through firewall. My guess is the ALG on the firewall if this is your setup.

Sounds like a port on the firewall is closing when it shouldn't.

[alex]

So you have a firewall between OXE and Teamwork? I would test with another SIP device on public side to OXE through firewall. My guess is the ALG on the firewall if this is your setup.

Sounds like a port on the firewall is closing when it shouldn't.

Yes, ALG is enabled on the router. With the port - it's a good idea. I'll check with MyTW "Collect call quality" feature RTP data on the server.

[cavagnaro]

Now, why they moved TW to internet? Why not leave it on LAN and just NAT it to Internet? I guess they wanted the TW login and guest features available on Internet but moving the whole server makes no sense to me, NAT can do the job perfectly fine.
As OXE is now communicating to an internet equipment it is hard to have the whole picture of the interconnections. What happens if OXE calls another SIP equipment that is declared as EVM on the internet? Does it also fades? Maybe you can build a quick Asterisk, one of those on box, and try to do some tests with that being on Internet as well.
I'd put a hub on CS/GD board and capture the whole traffic or launch a tcpdump on OXE so you can see the whole traffic and see what is exactly going on.

[alex]

Now, why they moved TW to internet? Why not leave it on LAN and just NAT it to Internet? I guess they wanted the TW login and guest features available on Internet but moving the whole server makes no sense to me, NAT can do the job perfectly fine.

Well I do not know why they made such a decision.

As OXE is now communicating to an internet equipment it is hard to have the whole picture of the interconnections. What happens if OXE calls another SIP equipment that is declared as EVM on the internet? Does it also fades? Maybe you can build a quick Asterisk, one of those on box, and try to do some tests with that being on Internet as well.

Actually no possibilities to run any device to check it.

I'd put a hub on CS/GD board and capture the whole traffic or launch a tcpdump on OXE so you can see the whole traffic and see what is exactly going on.

MyTW can log RTP packets. I checked and found that some RTP streams coming from port 0!

[alex]

Checked RTP on MyTW server.
Very strange indeed

MyTW_RTP.jpg

You can see that port 0 (!) is used.
Looks like it is NAT/router problem 100%.

[letacla.alcatel]

It's 100% routing issue,

recheck all the network routing, firewall, internet routing, some where mask miss matching..!!

The RTP will route always higher end...