This is true for security reasons too, i don't want to give my 2FA number to anyone or any website that i will use only once in a while
Do note that some services aren't able to send SMS to virtual numbers in the US, for some reason. If that happens, try again with a virtual number in the UK or somewhere else, or if there is a voice call confirmation option that may also work for you as you can redirect the call programatically. Considering the phone numbers typically cost only $1/month each you can keep a few around to deal with this situation.