When I read your post it got me wondering because I use Three pay occasionally on my phone and I also have Three broadband. I’ve looked carefully at the Ts &Cs and it doesn’t specify (that I can see) whether or not you can use your broadband number but I suppose the answer is to try it. You obviously know your broadband number and Three pay isn’t something that needs to be enabled so if you quote it on something you want to use the service on it’ll either work or tell you to get lost. Customer service on 333 can also give you more of a definitive answer.
