I am using a VPN which makes me look like I am in France, I am verifying my phone num,ber that is in the UK, when I enter my number +44 (UK code) it says invali

That is what happens when you use VPN since it can't detect the IP address as the actual one it see the France VPN and that calls a fault and thus it says invalid. So not quite sure how this relates to the Browser since by default it doesn't use proxy or VPN IP address.