Vectrotel X8 has 128-bit encryption that can only be broken with two phones talking to each other. It is possible to decrypt a phone call, but it will take you a trillion years to do it. The company didn’t say how much the phone will cost but if you have some secret stuff to talk about, it just might be worth it. It’s possible to break the encryption, but the company says it’s possible it could do it with a trillion-year encryption.”]
Source: https://gizmodo.com/vectrotel-x8-secure-mobile-phone-175618