VOIP Troubleshooting

[TMBS]

Hi

 

Can anyone help with VOIP issues? Our Business Manager decided to install them across our school without discussing with me - as is often the case they just appeared! We don't have managed switches, VPNs, etc just a flat network.

 

We've had constant issues with the phones since they were plugged in: crackling lines, not able to dial out, calls cutting off mid sentence. I've managed to get out broadband provider to put QoS on the main IPs but we're still getting issues.

 

Is there anything I can do? Any way of monitoring the traffic to and from the phones?

 

Thanks

Tracey

[pantscat]

Hi Tracey,

 

What make and model switches are you using?

 

Ant

[Willott]

Some more info about the VoIP service would be useful - is it fully hosted, or do you have a local PBX? If local, do internal calls drop as well? What make/model phones (most of them will have ability to SIP log etc)

[FN-GM]

Is it external lines only or internal as well?

 

Is the PBX hosted?

 

What phones do you have?

 

What speed internet, and switch uplinks?

 

How are the external lines provisioned?

[TMBS]

Thanks for the replies!

 

Our broadband speed is 100mbs/100mbps.

We have a Panasonic PBX on site and Gamma SIP Server.

The phones are Panasonic KX-NT551.

The issues are not happening internally.

We use a variety of Netgear switches: FS750T2, JGS524E, GS748T X2 most are connected via fibre.

 

As you can probably tell I have limited Network experience...

 

Thanks

Tracey

[supawat1]

Is your broadband provide voice optimised or converged broadband?

[Blue_Cookeh]

Thanks for the replies!

 

Our broadband speed is 100mbs/100mbps.

We have a Panasonic PBX on site and Gamma SIP Server.

The phones are Panasonic KX-NT551.

The issues are not happening internally.

We use a variety of Netgear switches: FS750T2, JGS524E, GS748T X2 most are connected via fibre.

 

As you can probably tell I have limited Network experience...

 

Thanks

Tracey

 

Do your phones have a 'diagnostic' screen? I know most Cisco and Avaya phones do - this will show things like Ping, RTT, Jitter whilst in a call. I'd be looking at that (your internet connection quality) - it's obviously not an internal problem if you can dial other extensions with no issue.

 

FWIW we're running our Gamma SIP trunks over a 20/5 FTTC connection via KCOM with no issues (separate from our main Internet connection). I do QoS on our firewall to give VoIP traffic priority and 4Mbps guaranteed bandwidth.

Edited February 6, 2017 by Blue_Cookeh

[TMBS]

Is your broadband provide voice optimised or converged broadband?

Sorry I have no idea...

[Meldrew]

We run a VOIP system on a flat network, no QoS with gamma SIP (via a reseller) and no problems that can't be easily explained. We have the occasional report of a cracky line which is always the handset wire faulty (our phones are mostly over 5 years old now). Unable to make a call - all the outgoing 'lines' are being used. Call got cut off - the other end got disconnected for some reason.

If everything is fine internally then your network is coping fine with it - after all its only something like 50kb/s data stream.

 

The only issue we did have originally is the codec that the phones used was incorrect. Having changed the codec to one that our PBX better supported the call quality was much improved.

 

Meldrew

[FN-GM]

What firewall have you go? I know someone such as Sonicwall will need specific SIP settings to be changed to allow for SIP trunks.

 

Also have you checked your firewall rules are setup correctly as recommended by Gamma?

[TMBS]

Do your phones have a 'diagnostic' screen? I know most Cisco and Avaya phones do - this will show things like Ping, RTT, Jitter whilst in a call. I'd be looking at that (your internet connection quality) - it's obviously not an internal problem if you can dial other extensions with no issue.

No I'm afraid not. Nice to know it's not internal though...

[supawat1]

Sorry, I was referring to these sort of services Voip Unlimited Voice Optimised Broadband - Voip Unlimited and Broadband | Gamma

 

Although it could be as simple as changing the Codec as Meldrew mention

[TMBS]

What firewall have you go? I know someone such as Sonicwall will need specific SIP settings to be changed to allow for SIP trunks.

We moved to our current broadband provider (Schools Broadband) the week before the phones went in and use their Fortigate firewall. They worked with the phone company the week they were installed as we were having issues and say that everything has been set in the SIP settings. I've only just gained access to the firewall but don't want to mess around with it at the moment as I have no idea what I'm looking for.

 

It's a shame we didn't install the phones before the broadband changeover as it would be nice to know if it has anything to do with our current provider whose service has not been the best...

[mtillbrook]

The problem will probably be a combination of switches that won't cope very well with SIP and other traffic on the network.

 

When I have seen this before on fairly simple flat networks, I've needed to VLAN out the voice traffic and its all works fine. You may well be able to do simple port based VLANing with those netgear switches which would do the job but it depends on links between switches etc!

To be fair, the company who installed the system should have done a survey of your network and looked at all these things first!

[FN-GM]

The problem will probably be a combination of switches that won't cope very well with SIP and other traffic on the network.

 

When I have seen this before on fairly simple flat networks, I've needed to VLAN out the voice traffic and its all works fine. You may well be able to do simple port based VLANing with those netgear switches which would do the job but it depends on links between switches etc!

To be fair, the company who installed the system should have done a survey of your network and looked at all these things first!

 

I don't agree. The issues do not happen on internal calls. It happens on external calls meaning its an issue with the SIP trunk that is routed via the internet. So the issue is somewhere between the PBX and Gamma. If internal calls are impacted I would agree with you.

[pantscat]

I agree with @FN-GM - my initial hunch was that the problem would be internal as I see that quite a bit, but in this case it definitely appears to be a problem between the PBX and SIP provider.

@TMBS Do you by any chance have a backup ADSL line with your ISP that you could use for testing?

[SchoolsBroadband]

Sorry I have no idea...

 

 

 

Hello @TMBS,

 

as it looks like we're the broadband provider can i suggest the following

 

1. put your phones on a completely separate VLAN to all other devices.

2. We can install a dedicated 2Mbit VLAN onto a dedicate port on your router. This then terminates into a virtual interface on your Fortinet firewall and will by pass Lightspeed. filtering too. By doing this we guarantee VoIP 2Mbit across our core and our carriers network.

3. What codec are you using and how many concurrent calls are you wishing to make? Gamma defaults to G711a i believe but you can also use G729 which uses less bandwidth. if you need more then we can give you a bigger sized guaranteed bandwidth.

4. Do you phones run passthrough? i.e. do they have PC's plugged into them at the moment? This is sometimes done to save on CAT5 sockets. Your phones should still be VLAN aware but your phone system company many have to configure this.

5. We sell Gamma SIP trunks ourselves and have few issues with them once in and working. if you wanted to we could migrate the SIP trunk to our account with Gamma and we can take charge of it all meaning we can do diagnostics at Gamma's end into our network from their equipment rather than playing Chinese whispers between us, your current supplier, you and Gamma.

6. Alternatively you could buy a Gamma Assured IP broadband, make a separate VLAN and plug all phones into that. We or your current supplier should be able to do this for you.

 

Send me a PM and I'll be happy to help.

 

Thanks

 

Dave

[TMBS]

@TMBS Do you by any chance have a backup ADSL line with your ISP that you could use for testing?

 

We've just this week has one put it but it's not configured yet but I'll test once it is. Thanks!