>contact discovery In both situations I have to have a contact's information already to find them. For a ID/password, you need your contact's ID to find them,

>contact discovery In both situations I have to have a contact's information already to find them. For a ID/password, you need your contact's ID to find them, for a SIM/# system, you need their phone number, every person I talk to on whatsapp or signal have given me their phone number, or vice versa, so we can communicate through those platforms. I had some friends that used Kik before, they had to give me their username. These two scenarios are exactly the same, in both cases I still need info from my contact before finding them. Only, an ID is more secure, because it can be used only with one service if you so choose, with a SIM/# you have to give your contact your phone number, allowing them to contact you through any other service you use that number with, whether you like it or not. I cannot see any benefits of that system for the user that you don't get from a ID/password and some cons that personally, I find unacceptable, such as the afore mentioned, seeing stranger's pictures and info just because they have a number my friend used to have, that's downright creepy and makes me wonder how many people who've saved my number can watch me on whatsapp and see when I'm online or check my profile out. Even people I do know, I don't necessarily want to see on there, employers, numbers i've saved for looking at places to rent, my ex landlord, clients i've had for work i've done. I don't need or want to have all these people automatically added to every chat program I install they also happen to have.