Configurations
of GSM/VoIP networks allow the service providers to avoid the local Wired
Public Switched Network (PSTN) in communication with a GMS mobile handset. As a
result, the high rates charged by telephone companies are avoided.
The function is available in some telephone networks and it allows
receiving the other call at the moment of the actual conversation by the method
of setting the active call in the waiting mode or cancellation. This will let
not to miss an important call and to agree upon time when it will be possible
to call back.