I have no concerns about them using my phone number. The reason for that is that I have never given my phone number to anyone online. I have two ways to get around any requirement to use a phone number. One — if it doesn’t require contact confirmation, I simply give my Mother-in-Law’s number. (I love listening to her complain about the number of telemarketing calls she gets.) Two, I dropped a cheap annual SIM card into an old phone, one that is not in my name. For $30 PA I have an anonymously owned phone. Facebook can do as it pleases with my data, none of it is real. Both my Facebook and Whatsapp accounts have been gathering virtual dust anyway — Facebook is only used for organising events and Whatsapp hasn’t been used since Apple sorted iMessage out.