If you have logged in to your account and now want to change the phone number which you are using to make calls there is an easy way to do it, please follow the steps:
1, Login to your Voxofon account on device
2, Press on hard "Menu" key and choose "Account and Settings"
3, Open "Settings" section from Account and Settings page
4, Tap on "This Mobile Number"
5, Change mobile number in "This Mobile Number" section and hit "Save"
That's it your new number is saved.
Please note you would need to verify your new number to be able to receive free calls and text messages to that new phone number.