Secret, anonymous messages aren’t just for the dastardly. Luckily, a little privacy isn’t difficult to get. With some effort and a spare phone, you’ll be whistleblowing, protecting your privacy from harassers, and staying anonymous when selling on Craigslist or looking for dates on Match. Here’s how.

Source: How to Create an Untraceable Messaging Device With an Old Phone

Basically install Hushed to generate disposable phone numbers, cyberghost / hideman for a free VPN service and someone elses WiFi.

Note – there are limitations to this project 🙂