Well tox works by connecting to a bootstrap server and then connecting to the user you want to talk to through P2P, so yeah just by sniffing the connection you _could_ get the other users IP (I haven't tried this myself, don't quote me on it). But, regardless of that, tox's crypto is soykaf. And they won't fix it, nor have any intention of fixing it. (https://github.com/TokTok/c-toxcore/issues/426
) If you want P2P stuff with built in anonymity, use Ricochet. (https://ricochet.im/
) If you don't care about centralization, then create your own Tor or I2P hidden IRC server for you and others to use. Mobile? Heh, yeah thats a stretch. Signal maybe.