The sync is so great, especially if you're trying to message with in-flight wifi. In-flight wifi usually only works on one device at a time which means you can'

The sync is so great, especially if you're trying to message with in-flight wifi. In-flight wifi usually only works on one device at a time which means you can't use Whatsapp from your iPad or laptop on the plane. You do need a phone number to register (I use my google voice number), but you can select who can actually see it on your profile. When you join groups, it isn't exposing it to others unless you add them as contacts - and even then you can disable from sharing with those contacts.