You can certainly move from one mobile device to another and keep your existing number! 

Simply log out of Hushed on your old device, and then download Hushed onto your new device and log in to your same existing account using your username and password. 

❗NOTE:  Please ensure you are logging into your existing account, and not creating a new account, because if you create a new account your number won't be there -- it's still on your existing account!