I'm guessing that this issue is now going to be firewall related, so will re-read a few of the posts above as I can see some have been tweaking firewall settings

Does anyone have any bright ideas as to what to start looking at next?

In reply to a post by Swervin_:

I'm guessing that this issue is now going to be firewall related, so will re-read a few of the posts above as I can see some have been tweaking firewall settings

Does anyone have any bright ideas as to what to start looking at next?

It's fully working finally. Turns out I just needed to make a proper call from it, rather than test dialling my mobile. Can now make and receive calls.

Post deleted by Spudgun

Post deleted by sebus

Edited by sebus (Fri 29-Mar-24 11:18:16)

Post deleted by sebus

I know this is an old thread, but if anyone is still interested, it is fully possible to use an own router with Zen over CityFibre -- provided your own router is a good one. My solution with a Ubiquiti EdgeRouter is described here..

https://community.ui.com/questions/EdgeRouter-as-pri...

As many people are struggling with using the Fritz!Box with Zen in IP Client mode behind another device doing NAT, after many years of absence, I have re-registered to explain what is going on for those that have failed to get it to work.

Zen's Digital Voice (VOIP) service, assumes that the customer will be connecting the provided Fritz!box router directly to DSL or FTTP. This would mean the Fritz!box would have the public IP address on its WAN port, making it easy for it to send and receive calls using the public IP address.

If, like me, you have your own firewall, (in my case OPNsense), or another router, instead of the Fritz!Box connected to the internet. Some additional setup is required for successful incoming calls. In my case I have the Fritz!Box connected to my OPNsense firewall to provide VOIP telephone service and act as a DECT base station. You don't necessarily have to use the Fritz!Box, you can use other VOIP devices or a SIP PBX like Astersk if you prefer.

The first thing, as has been mentioned a few times is, ports must be forwarded from Zen’s VOIP servers to IP address of the Fritz!box, using the information provided by Zen in their help document general-sip-settings While this will allow the incoming call to be initiated, for some people, depending on the type of NAT you have, this may be enough calls will drop out after approximately 30 seconds.

In addition to the inbound port forwarding rules, you will also need to make sure that you configure your outbound NAT, so that connections from the Fritz!Box have static ports. On PFSense & OPNsense this can be done as follows...

1. First go to the Firewall -> NAT setting menu, click on outbound. Set the NAT mode to ‘Hybrid outbound NAT rule generation’.

2. Add an outgoing rule for the IP address of the Fritz!Box...

Interface: WAN
TCP/IP Version: IPv4
Source address: Fritz!box IP address
Source port: UDP/*
Destination address: any
Destination port: any
Translation/target: Interface address
Static Port: yes

Save and apply this rule.

Why this second step is impotant

There are different types of NAT available, but most dynamically generate new port numbers on out going connections, i.e port address translation as well as address translation. While this works for many things, SIP is one of the few protocols where this is a problem. SIP expects the source port to be the same as the destination, in this example port 5060. When the outgoing port is changed from 5060 to a random port by your firewall's NAT, the connection will fail.

The failure is due to the call sett-up being a 3-way process...

1. The incoming call sends an INVITE to your public IP address on the SIP port 5060, this is forwarded to your Fritz!Box according to your port forwarding rule, the phone starts ringing!
2. The Fritz!Box sends an OK response so the call can be set-up, but this needs to have a source port of 5060, not a random port.
3. For the call to be successful, the server will need to send an ACK response to Fritz!Box, to acknowledge the OK sent. Herein lies the problem, the OK response will be sent on the same port that the OK was received. Using the common dynamic port mapping on NAT, this will be a random port. As there is no corresponding port forwarding rule matching the random port, to receive this connection on, the ACK response will never be received an the call dropped.

Setting a static port on the outgoing NAT, ensures that the outgoing port remains 5060, now when Zen tries to send the ACK to your public IP address, you have a port forwarding rule that forwards requests to port 5060 to your Fritz!box, the ACK is therefore received and the call stays up.

Hope this helps some people.

PS, my old forum username from many years ago that got deleted through non-use was 'Going_Digital'

Edited by Tandy (Sun 05-May-24 10:05:31)

Re: Own router and digital voice methods

Thanks very much - I've filed that for useful future reference because Zen aren't broadcasting and attitude of great helpfulness on the subject.

In reply to a post by rikur:

A few things I learnt from the Zen digital voice migration:

1) Zen use what I call traditional SIP - i.e. connecting to a fixed port on a fixed IP address (whereas many other VoIP providers use the SIP registration initiated by the client to give the IP address and port). Therefore it only works 'on net', you cannot use from other connections.

I realise this is an old post but it’s the only place I’ve seen this mentioned and wondered if anyone else can confirm that Zen Digital Voice does not function, for example, when the Zen SIP settings are entered into a soft phone app such as Groundwire as installed on a smartphone which is being used away from home.

Thanks.

I don't suppose you got your W70B working with Zen?

Many thanks!