Digital networks can disable a mobile phone completely using its IMEI number. Mobile networks can track this number through calls made on their networks and if a person tries to re-register a phone that is reported as lost or stolen they will be identified. The system automatically blocks or unblocks a handset on any GSM network by sharing information in a central database called the NetVisa CEIR Platform, a form of National IMEI Clearing House. All Mobile Network Operators both GSM and CDMA send a list of phones to be blocked or unblocked each day or in real time and also receive the details of phones to be blocked or unblocked from the other service providers. This means once a lost, stolen or found mobile phone has been reported to a service provider it can be blocked or unblocked within 24 hours.