Yes! In order for Sideline to give you perfect voice quality the app uses radio towers to transmit voice signals (same as your phone carrier) to make calls. For this purpose, we need you to register a phone number (cannot be a voIP number) as a mandatory part of the account creation process.
For any additional questions, feel free to contact us.
If you don’t have a number, you may be interested in our other application, Textfree!
If you recently got a new phone or changed your mobile number, simply login just as normal. All your account information will transfer over on its own!
If you experience any trouble with this, please do not hesitate to contact us-we'd be happy to help!