Can't use Voip phone

[Suki2]

After switching to Sky, I used the voip phone connected to the router for a year, but suddenly it doesn't work. When I look at the phone, it says that it's connected to the internet, but I can't make or receive calls. When I asked an expert, he told me to open several ports. UDP5060-5070, udp7000, udp 20,000-60000, udp123, tcp 10080, tcp80. I opened the ports instructed by the Sky app, but it didn't work. What could be the problem?

[Chrisee]

@Suki2 what colour Sky hub do you have?

[Suki2]

I Have a white one