Incoming audio drops out when another call comes in. BLF lights not working.

[fergus4]

Our system has been up for a few months and seemed to be working fine until I added an additional Fanvil x4 phone. When doing so I saw that the other x4's firmware was out of date so I upgraded all the phones. We use stun for provisioning to a cloud based 3cx system. We have two Grandstream phones also that do not seem to be having these issues.

Since the updates some phones seem to experience garbled audio with dropouts when another call comes in. Also the BLF keys seem to go out on some extensions. Rebooting the phone or the server seems to fix it for a short time.

I have since staggered he sip and rtp ports for each phone in the local router. In addition to disabling SIP ALG I have now disabled spi in the router.

3cx version 15.5.0

 

[cobaltit]

Did you stagger the ports in the phone provisioning tab for each extension first, then re-provision the phones and THEN made the firewall changes?

Losing audio when another phone makes a call seems like a firewall issue but anything affecting call quality is either a network/internet quality or bandwidth issue. Your setup seems like a good candidate for a setting up a SBC.

 

[eddv123]

I would definitely agree with @cobaltit on this one, both phone brands you have will work for PnP across the tunnel.

3CX only actually recommend STUN for 1 or 2 handsets per site now it is messy and a presents security issues.

Does your firewall checker pass completely now you have made those changes?

 

[fergus4]

I did not realize stun was so limited. I do not see any suggestion in the docs that it is so limited and I only found the port incrementing in an obscure forum post.
Yes, I staggered the port numbers (Incremented, SIP: 5067, 5068, 5069... and RTP port ranges: 14010-14019, 14020-14029, 14030-14039 ... etc)

Firewall checker passes all test but I thought that it is checking firewall associated with server. Does it check the local router firewall at the remote site too?

Bandwidth should not be an issue 150 Mbps up and down.

I'll Set up an SBC if that is the best solution.

 

[eddv123]

It's not so much that it is limited, it is just the method for setup is as if you are creating each endpoint as a separate connection, the SBC sort of bands all the remote extensions together if they are on the same physical site.

The main downside of STUN I think would be it'd lack of security.

 

[fergus4]

eddv123
Are you saying that I can have 6 or more extensions on a stun setup? And what is the method you are referring to...the incremental port addresses?

 

[cobaltit]

You can have as many STUN phones in one location as you can allocate ports. It's more of an admin headache that makes the SBC a superior solution when dealing with multiple phones.

Here is the official guide on configuring STUN phones:

https://www.3cx.com/docs/manual/configuring-ip-phones/#h.ul2fzupi6t22/

The 3CX firewall checker only changes the firewall on the 3CX instance. It doesn't (and can') check the firewall at the remote sites.

 

[fergus4]

Well I'm pretty sure I have STUN set up correctly but I still have issues.

Why does the RTP audio travel over these ports on the server:

1. UDP ports 9000–9255 – used for RTP traffic – audio.

But on the local router for the remote extensions you open ports in the 14000 range?

 

[cobaltit]

Because you have two ends of the conversation . The current range is 9000-10999 on the server side. The 14000 range (can be any range really) is for the endpoint. So a call between 3CX and the endpoint would be from 9000-9001 on 3CX to 14000-14001 on the phone (1 port for each direction).

 

[eddv123]

@fergus4

@cobaltit has answered the question posed but thought I would simply add a little extra insight from own experience.

Setting up multiple handsets using STUN can present very sporadic behaviour, I have known deployments go well and others not, but to quote @cobaltit they are a real headache when they don't.

Also audio paths. Each endpoint is seen separately by 3CX where with the SBC funnels all paths via it's built in tunnel (which also adds encryption and security).

With STUN however each path must traverse the WAN back to the PBX which not only puts extra load on the PBX (PBX delivers audio) but call transfer, shared parking can be an issue on the remote site also.

 

[fergus4]

OK, set up SBC and provisioning went well..no issues. Some light testing ...everything went well. First day office open...disaster. Worse than ever!!!! Extensions ringing constantly after call picked up, No connection/audio when picking up a call, drop outs on incoming audio when another call comes in while on a call.
I thinks its an issue with the new update for Fanvil x4 phones.

 

[cobaltit]

So I loved the LCD for BLF keys on the Fanvil and the ability to screenshot the display from the web interface but other than that they are shaky. Did you factory reset the phones and use PnP to provision them after installing the SBC?

 

[eddv123]

Personally I am not a fan of Fanvil I have found too many issues with them, Yealink and snom I find to be a more reliable set of preferred 3CX phones (in my experience).

Despite this a lot of your issues could be related to the firewall I think, SIP ALG and port forwarding correctly.

Have you tried the firewall checker?

 

[fergus4]

Yes, firewall checks no issues. No SIP ALG. It has gotten worse now since I switched to SBC.

I see a lot of others with issues with Fanvil x4 since upgraded firmware. I'm going to try reverting back to older version.

 

[fergus4]

I have down graded the fanvil phones to the previous firmware: 2.4.0.5572. I won't know till Monday if they are working any better....They don't show any issues until the whole office is in using them.
I did notice that the Fanvil website has 3 firmware updates posted since 3cx's last approved firmware update. Sounds like they had to fix a few things since 3cx tested its current approved version.