A group of users can be created with a purpose of receiving voice announcements through the speaker of a telephone set, but it has to be in the waiting mode.
“Call filter” allows blocking/unblocking the incoming calls as easy as to make filtration, it also journalizes all rejected calls. It is very convenient if you do not want to receive a call from some subscribers, when they will call you, “Call filter” will do so that your line is engaged.