It's pot luck as to if WiFi calling works with them, I know that some (maybe all) Nokia's don't work, some Sony's, and no Pixel's work. Their handling of this as been appalling, when gf's Nokia didn't work they blamed the phone, then when I pointed out it showed as a supported phone they blamed Vodafone saying some early versions of her phone wern't supported by Vodafone network, last summer we where passing a Vodafone shop and they kindly checked and the phone worked with a vodafone SIM, soon after gf broke the phone, she brought a Sony which showed as being supported, once again it didn't work, they sent out a new SIM, still no luck, we kept raising a case and after all the standard questions and suggestions they would say it was being passed onto tech managers and they would reply within 3 days, we never once got a reply from the tech managers. When gf and myself swapped SIM's we found her Sony and My Pixel worked fine on 1p mobile (EE network) but neither would work on Lebara, eventually got customer services on a voice call, and this one didn't do their favorite trick of cutting me off after 20mins, it was passed up the line and eventually they had to admit that WiFi calling on their network doesn't work correctly on many phones.