This is a terrific question! In general, your number should be completely masked for inbound and outbound calls provided that you place outbound calls using your NumberBarn account or mobile application. Here's an article that helps:
One word of advice and caution, if you are forwarding calls to your mobile phone, is to make sure that you set a voicemail greeting on your mobile phone. Many wireless carriers will set a default greeting on your phone that reads your cell phone number off to the caller.