Most allow certain phone numbers to be blocked for calls to a subscriber connection within their networks. However, in some cases, an extra fee is charged for this feature and subscribers have to commission the provider with setting up each individual call block. Modern IP-based connections frequently offer customers the option of setting up and managing call blocks themselves via web interfaces.
If you have your own telephone system or Internet access router with telephone system function or use a , you can block calls directly via the user interface of the router or system. In this case, the call is put through to your connection, but then rejected by your own telephone system. Comprehensive statistics functions generally provide information about all rejected calls. High-performance systems even allow you to define time-dependent call blocking rules.
Many end devices, such as smartphones, also have functions for blocking certain phone numbers. In addition, phone numbers can be blocked for individual services such as text messaging or chatting.