A blocked call in telecommunication terms is a telephone call that fails to reach the desired recipient because the recipient’s hardware is programmed to block or reject a call from that particular caller. This blocking of calls can happen due to multiple reasons. It may be that the receiver has purposely decided to block the calls from the caller and has programmed his device to block the calls or has asked his telecom service provider for the same. Another reason can be that the network is highly congested and the system has been programmed to block the calls if it is operating at maximum capacity.
In these modern times, blocking a caller from calling your mobile number can happen at the tap of a button. Once you have blocked all incoming calls from a particular number, he or she can still call you but the call will not ring on your phone and they will hear the message that you are busy on another call. However, it might also happen that even without blocking a caller his call coming towards you is blocked. That will happen only if the phone lines are running at full capacity and can not handle any more calls.