Matthias Grob
to be dependent on a phone number is terrible for those who travel and end up passing the local number + the whatsapp number to people the meet.
this is a helpful comparison but completely missleading in one aspect: to call a phone means to call anyone who has a phone number, including land lines Whatsapp and most others can not do it, but f. ex. Skype can
an important point for comparison: availability on various machines. whatapp for example only works on the computer when the phone is close. if you loose the phone, there is no way to register whatsapp on another machine until you get a new SIM. Skype does not only work on any machine but simultaneously: you can type on one, speak on another (with the same registration) and even: if you talk on one and someone calls you, the call goes to the other machine