One of my US friends recently ditched her landline and now has only a mobile. She gave me the number, when I rang she said the display showed 'private number'. She has a basic calling plan with international calls and texts barred, so she can only call or text the US, Canada and Mexico. Is there anything in the phone or network settings we could check in order to get her phone to display my number so that she knows it's me calling? Alternatively would she be able to call or text me using whatsapp?