You may not entirely grasp the concept of centralization. Even if you were able to fully replicate the workings of Telegram's IM server, you would still need to migrate all your contacts to your $REIMPLEMENTED_SERVICE! Thus, again, why would a FOSS developer want to do that and not use Jabber???

That's exactly, BTW, my main problem with centralized services.

Compare the Jabber approach. If you distrust your current Jabber server, you switch to another one or even deploy your OWN one! You can still talk to all your previous contacts! Only those contacts who also distrust their current server would need to migrate

And as of today, not everyone uses Telegram (I don't know of anyone using it yet, even in Spain), so... why are you already assuming everyone uses it? This is a self-creating problem!

See above: I run my own server. Is there any other option that could give me more confidence?

No, they want to capture as many users as possible in the least amount of time, like any other dot com bubble startup. Because of network effects and because people never learn, those users will have a hard time leaving their network ("but all of my friends are on Telegram instead of $TELEGRAM_SUCCESSOR!"). And once they have everyone by their balls, they'll start adding dibous "features", make an IPO, buy a private jet, etc.

And since you are a fellow spaniard, I'm sure you remember the "MSN Messenger" era. Have you _counted_ the number of times "everyone" has moved from one IM service to the next one? What surprises me most is that on every one of those mass migrations users have _lost_ features yet they don't seem to realize.
Just to give an example, when I asked the "Why don't you use Jabber?" question in the MSN Messenger era, someone answered "because MSN allows me to play online Billiards with my contacts!".


Might be a right time to link this: http://www.gnu.org/philosophy/compromise.html