Why phone-numbers only?


Hi there

One of my main concerns of messaging-apps today is the use of phone-numbers as the only option for usernames.

In my eyes, this is a mayor drawback:

  • mobile numbers are registered to the person who bought it
  • It makes it hard to have multiple accounts for different purposes
  • Phone numbers are spread widely which makes it hard to limit the number of people you want to contact you on a given channel/app

Since you are working on a communication app, I can imagine that the idea might seem odd to limit the range of people to communicate with:-) But yes, there are contacts on my phone, that I don’t want to get in contact with if I can avoid it. (And no, “blocking” them is no option, turns out this hurts peoples feelings). I also have multiple mail addresses and google accounts etc

Is this phone-number-concept set in stone or are there any plans to get rid of this?

Btw: Why would my mobile device need a phone-number directly assigned to it some years from now? This concept is pretty old and VOIP removed this dependency for wired-phones years ago.


Hello @shrank,

TL;DR: no, the user ID is not changing anytime soon. Kontalk was designed this way and changing this would mean becoming another project.

There are a number of reasons why Kontalk was designed to be used with phone numbers.

It’s an easy and common way of identifying a person. You usually have your friends/buddies phone numbers in your contacts. It’s also easy to use the auto lookup feature and less heavy for the servers (remember Kontalk should be cheap also for server administrators, imagine if we would have to find matches for any user identifier in your contacts).

Less spam. Spamming on mobile numbers is much more expensive for a spammer than using a free system (free as in easily and anonymously accessible). Concerning privacy and anonimity: Kontalk is safe (as in privacy), but not anonymous. We knew from the start that using phone numbers would have meant sacrificing anonimity (see next point).

We aim to provide a free community-based communication system, easily accessible and usable by anyone. People feel natural to link their person to their phone number. Again, about anonimity: you can’t have usability without sacrificing a little from other aspects of the design (in this case, anonimity).

SIM cards can be used with other devices different from mobile phones as well (think tablets, or 3G modems capable of receiving SMS). It doesn’t matter: your number is your identity. Or maybe I’m not understanding your point in this question.
Another note on this: if the phone number is dismissed (e.g. expires) and then recycled to another person, the new Kontalk account will override the old one, throwing out the old account owner (since he/she is no longer the owner of the phone number).


To me, the main benefit of Kontalk compared to other XMPP servers is that it doesn’t lose my messages if I’m not connected when someone sends me a message (I know in theory other XMPP server can do the same, but in practice it seems to be a rarely supported feature of existing public XMPP servers).

And luckily I can use it because I indeed have a hone number that I can use for it. But that number costs me $20 a year, even if I never use it, so I’d rather spend those $20 as donations to Kontalk and use an identifier that’s not linked to a phone number.