The 3CX mobile app is not a standalone app. You need to configure the 3CX communication system with extensions and SIP trunks. If you need help with this, please contact your 3CX partner. If you are confident that this has happened; then the administrator will send you a welcome email to configure the 3CX app. Or you can just: Scan the QR code Click the mobile device configuration file. You are ready to use the 3CX app.