[Here's how signal does it](https://hub.packtpub.com/signal-introduces-optional-link-previews-to-enable-users-understand-whats-behind-a-url/ https://hub.packtpu

[Here's how signal does it](https://hub.packtpub.com/signal-introduces-optional-link-previews-to-enable-users-understand-whats-behind-a-url/ https://hub.packtpub.com/signal-introduces-optional-link-pre...). TL;DR, the app establishes a TLS connection directly between your phone and the site, but routes it through a proxy on Signal's server, thereby hiding your IP without being able to view the URL. I imagine Whatsapp works in a similar fashion