The services provided by professionals in particular field. For example, a company may charge a certain sum of money for the certain tasks their consultant accomplished for the company who ordered the service.
“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.