Things You Can Do in 3 Hours` The developers of Tumblr created a post-by-phone feature that allows users to automatically post updates from their phone to their blog after entering their phone number and an optional PIN. This feature is made possible by Twilio's API, which provides a simple way to integrate voice calls with online applications. The feature was likely developed quickly, as it was announced just a few hours after being discovered, with the developers possibly enjoying a celebratory meal afterwards.