CLAIR Registration Form Q (Japanese Number?)

Hey guys once again I am relying on this amazing source of help and community so thank you so much in advance for any help you can give this fool haha.

There is a CLAIR registration form that is due prior to my departure date (UK) that involves my placement details as well as helping me set up my Japanese lessons. Within the form it asks for my phone number but also states that international numbers are not allowed. As the form is due prior to my departure I am confused whether this means I need to have a Japanese number sorted before I arrive or whether they mean international numbers excluding where I am originally from. I could ask at the physical orientation before leaving but depending on their answer it could be a race against time.

Thanks guys like I said any help is really appreciated 🙂