Digital to IP phones in SCN

[wlamo]

I have 4 offices connected in a SCN. 3 IP500s and 1 IP406 v2. All inter-office calls work fine with the exception of when someone calls from a digital handset to an IP phone. The call goes through but there is no sound. I have "Allow Direct Media" turned off on the IP lines at both ends and on the extensions. The funny thing is If the IP phone calls the same digital handset there is sound.

 

[Bas1234]

Check your IP routes.

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It works! Now if only I could remember what I did...
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[wlamo]

My route config is set to IP Address 0.0.0.0 IP Mask 0.0.0.0 and Gateway IP Address 10.0.100.1

All my systems have a similar route that is set to their subnet.

Can you tell me if there is another route config I should be putting in?

 

[piethief]

The more specific the route the better. I have had 0.0.0.0 work and not work.

 

[wlamo]

should the route be the next hop? or the IP of the other IPOffice?

 

[piethief]

network of other IP office, I usually leave the last value as 0

example 192.168.1.0 with that networks local gateway.

 

[wlamo]

without the Destination?

 

[CLWINGET]

Try turning off 'ENABLING FAST START' in the EXTENSION tab of the IP User and the IP LINE.

 

[piethief]

if the phone connects, voice path only issue, make sure UDP is not blocked in either direction.

 

[CLWINGET]

good point piethief - defintely check the router/security gateway and make sure it's not blocking the TCP/UDP ports necessary.

 

[wlamo]

I did turn off "enable faststart" and that killed all comunications via IP lines. Since this all requires reboots I have to wait till tonight after hours. I will test the UDP idea tomorrow but our router admin told me he doesn't block anything through our VPN's.

I am grateful for all the input.

 

[tlpeter]

No voice is a routing problem
So start looking in your network


ACA - Implement IP Office
ACS - Implement IP Office
ACA - Voice Services Management
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Women and cats can do as they please and men and dogs should relax and get used to the idea!

 

[SuperJenks]

Are the phones on the same subnet as the IPO? If not, do you have a return route in the router/gateway back to the IPO?

ACS IPO-I

 

[tanderson3733]

Although your router admin may not be explicitly blocking anything on the VPNs, the VPN devices may be mis-handling the VoIP traffic. Keep in mind that back in the day of old-school network security, firewalls simply acted on IP Address and TPC/UDP ports. When applications like VoIP started becoming mainstream, this threw a big wrench into that process - Call setup and control DO use static ports 1719 and 1720, however the actual voice path uses dymanic ports. Someone told me once they heard Forrest Gump say "VoIP is like a box of chocolates..."
You didn't say what type of VPN equipment is in use, but from my Netscreen/Juniper SSG experience these use an Application Layer Gateway, inspecting any traffic that crosses zones regardless of IP Address or Port - like it says it's an Application Layer protocol. NetScreen's ALG inspects H323 traffic as part of it's screening process, and previous versions of their operating software didn't do too good of a job of it. The result was no voice path. The short-term fix was to uncheck H323 in the ALG settings so that the firewall wouldn't inspect that application, just let the traffic pass. Lower security? yes, but if I'm not mistaken they've solved the issue in later releases of NetScreen OS.
Your VPN equipment may have a similar issue, without knowing more about the equiment it can be hard to tell.

 

[wlamo]

Hmm, food for thought on the post from tanderson3733, thanks. We are using SonicWall for our firewall; I'll have the Firewall admin look at that very scenerio. If I uncheck H323 it should still communicate?