Intermittent one-way audio and phone unable to hang up 3

[Straggle]

Hello all.
I have an IPO 500V2 on 11.0.4.7 release 6 with intermittent one-way-audio on certain IP phones (9608s all).
The user will be on the phone talking and before long they will begin the stands that they cannot hear the calling party any longer. Testing reveals a decline party can still hear them all the time, but not vice versa. The telephone is still on and lit, and the call counter is still counting upward. They will try to hang up the call to call the party back and the phone sometimes takes up to a minute to actually hang the call up. This could happen to her because the row and then not again for hours.

I have rebooted the phone system a few times, and even did an update from an early release to 11.0.4.7 release six and don't see any changes in this behavior.

I just spoke to Jenna (my distributor) and they recommended they remove every codec from the IP extensions except forG.711 ULAW. I have now done this.

Anyone seen this before? Any ideas?

Thanks!
Chris

 

[PhonesTech]

I'd start by checking what's common between those phones that have issues? Do those phones get used the most? Firmware on the phones? are they on same switch?

 

[Westi]

You give not all info so I will guess

It is a SIP trunk and their calls are to an outgoing party.
Let me take another stab at it, it is a Sonicwall firewall and the calls last about 11 minutes.

I might be completely off (happens more and more ) but more information is better

Joe
FHandw, ACSS, ACIS

"Dew knot truss yore Spell Cheque

 

[IPOLackey]

I'm with Westi, Sounds like a NAT issue on the firewall.

 

[Straggle]

Re-opening this discussion.
The telephones (5 of them) are all on the same HP "HPE-1920" switch, and are ALL IP phones. None of the digital stations are experiencing the issue. The IPO NAT ports are default as 49152 through 53246.

The system has a standard 23 channel PRI for all inbound and outbound calls.

Any ideas? I have reached out to their data vendor with this same info.

I don't mind attaching the config if that'll help.

Thanks all!

 

[IPOLackey]

Oh Straggle...


Right, so voice over IP works by using a signalling protocol, either H323 or SIP, and a media protocol, RTP. What you describe as the "NAT Ports" are the RTP ports the IP Office will use for the IP Media(The audio of the call). NAT is a Network Address Translation and is used when the 2 ends of the call are on different networks. (For SIP then it's usually the SIP ALG on the firewall/router that causes issues)

As we're looking at an ISDN line we can discount any possible SIP issue, and look at how the network is configured. Questions you need to ask are,
1. Are the phones and the IP Office on the same network, ie, have IP Addresses in the same subnet?
If Yes, then you're possibly looking at a dodgy cable, or maybe even the VCM in the IP Office failing.
If No, then you need to look at the firewall for the NAT timeout issue. One Way audio and a lack of response to signalling commands (pressing hold or hanging up) means something along the way is blocking that traffic, or has lost it's route/translation.

You're going to want to connect a PC to the voice vlan(so same IP address range, mask and gateway) in the same switch the phones are in. Then use Wireshark(if you know how to mirror ports and read the packets) or at least do some ping tests/traceroutes from there to the IP Office. This will tell you if you're getting any packet loss or possible routing issues.

Hope that points you in the right direction.

 

[Straggle]

Thanks all, we seem to have rectified this. The IPO is using 10.0.0.10 as the LAN IP, and the phones were DHCPing on their own VLAN in the 192.1.1.x range; therefore the traffic was passing through the firewall. As you guys mentioned that was the issue.

Here is the report from the data vendor:
Melissa mentioned that the audio drop usually occurs after she has been talking with someone for an extended period of time. This made me recall that the SonicWall can have issues with keeping UDP sessions open because it has a default UDP timeout of 30 seconds. I have increased the timeout to 300 seconds which is what most VOIP manufacturers will recommend when installing a SonicWall firewall.

Anyway, thanks everyone!

 

[Westi]

Sonicwall = phone problems

I have never had that many issues with another brand of firewall.

Good to hear that you have resolved it.

Joe
FHandw, ACSS, ACIS

"Dew knot truss yore Spell Cheque