P10 plus 4g supervoice

[Passat73]

Can anyone help. I have recently purchased a sim free P10 plus from an eBay seller. I wanted to use the 4g super voice feature on the UK 3 mobile network. After setting the phone up it appears this feature is not working. I have contacted 3 and they have told me it is not available on my phone. I have also contacted huawai and they have not been able to help. Can anyone offer any assistance as this is a feature I really want. Is rooting the way to go?