NF18ACV Firmware Update Required

I am with contact energy fibre in Auckland. I see that the Vocus list of ISPs doesn't mention contact. However I have seen the name Vocus in my settings.

I updated to a generic firmware for my NF18ACV router. I didn't realise this was a bad idea. I was able to get the internet working afterwards, but not my home phone.

This is the firmware I updated to.

NF18ACV-NC2-R6B17.EN

What's my next move? I either need to confirm that contact is Vocus, and update the firmware, or get the SIP settings to make my home phone work.