I bought a new 2 Degree's Samsung S8 phone in February this year. Since then I have been trying to get 2 Degrees wifi calling working through my home wifi without success. The phone switches to wifi calling and works on wifi calling when I am connected to  other wifis including a public wifi and a Spark hot spot set up on a Samsung Galaxy A3 2016 here at home. However, it does not work on my wifi nor my daughter's wifi which is a similar set up but 200 odd kilometres away from mine.

Both of these wifi systems use an Orcon supplied NetCom VDSL/ADSL WiFi Gigabit NF4V Modem Router connected via fibre to the internet.

I have put the problem to Orcon's online help but have ended up with them stating --- "I have queried this with our support teams and was told that base on what you have mentioned, this is an issue in regards to port forwarding and we do not provide support for this."

I guess one of the options for getting wifi calling working in my new office that is located in an area of bad cellphone coverage is to change my ISP. I am reluctant to do this as I have had good reliable service from Orcon for about ten years now. I would prefer to get wifi calliing working over my existing wifi.

I raised the question on the 2degrees wifi calling forum regarding what the requirements for wifi calling are and got the following response from SaltyNZ :

"IKE (tunnel setup) is UDP 500 and then UDP 4500 for IPSec main tunnel when behind a NAT. Your router must properly handle UDP NAT - you'll have to have one that does stateful connection tracking. I have an NF4V but I only use it as a PPPoE modem, not a router, so I can't comment on whether they can be configured appropriately or not.

You shouldn't need to open the ports specifically to an IP address, but the IPSec gateway is 118.149.14.20."

Consequently I have tried to set port triggering in my router to get ports 500 and 4500 to open when required by wifi calling but when I try to do this as a custom set up i get the message "Add port triggering failed". This message also comes up if I try to set up one of the internally held application settings got from the drop down window in the web interface to the router.

Am I trying to go the right way to get wifi calling working through my modem or should I be trying something else?