One Number service is a mobile service. You will be provided with a personal virtual communication number when you open an account at Business Office. This number will be published as your unique number. If other subscriber dials this unique number, the system will forward the call to the actual phone number according to your settings. The One Number service is applicable to those who have more than one terminal and are usually mobile. The One Number Service will integrate multiple terminals as required so that you can remember the number easily and contact with others as a mobile user, which adapts itself to the communications development.