Call blocking: Cloud telephony method explained

Call blocking directly within the telephone provider’s network
Call blocking via the router or telephone system
Call blocking on end devices

For various reasons, it may be necessary to block incoming calls from certain phone numbers. This applies, in particular, when recurring calls cause disturbance or annoyance; call blocking may then be the only way of getting some peace and quiet. Call blocking is technically possible at various different points: the telephone provider’s network, the subscriber’s own Internet access, the telephone system or the end device. When blocking calls, a distinction is made between so-called negative and positive lists. While negative lists only block specified phone numbers and permit calls from all other numbers, positive lists only permit calls from individual phone numbers. In the latter case, calls from all other phone numbers are automatically blocked. It is also often possible to block callers who hide/suppress their phone number.

Call blocking directly within the telephone provider’s network

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.

Call blocking via the router or telephone system

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.

Call blocking on end devices

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.