Call control is a method used in telecommunications networks to monitor and maintain connections that have already been established. Call control is used in voice over Internet Protocol (VoIP) systems to regulate connections between H.323 endpoints or between an endpoint and a gatekeeper. H.323 is a standard developed by the International Telecommunication Union (ITU) for digital communication between terminals, network equipment, and services. Call control is one of three key types of communications traffic in a VoIP network, the other two being call signaling and media communications. Q.931, a connection protocol for digital networks, particularly VoIP systems, is used for call control. Messages are transferred as octets in accordance with ITU H.245, which determines the type of call medium to be used (for example, traditional voice, videoconferencing, or VoIP) and then controls the connection once it has been created. Call control functions include, but are not limited to, determining master/slave status for endpoints, monitoring endpoint status, modifying connection settings, terminating a connection, and resuming a terminated or unsuccessful connection.
How Call Control Works?
When you enable Call Control, a caller will be required to input a number on their keypad the first time they call you. If they input it correctly, the call will be routed to you and they will not be prompted again (as long as they are one of your last 25 callers). If they do not input the proper number, they will receive an automated message stating that they have been unable to contact you. This screening mechanism keeps robocalls out while making it easy enough for real-life callers to pass.
You may add phone numbers to your Accepted list to avoid having them screened when they try to call you. We strongly advise you to add the phone numbers of regular or important callers (e.g., family members, school offices, physicians' offices, libraries, etc.) to your Accepted list, especially those who may utilize auto-dialing to reach you, as well as anybody who does not understand English or French.
If you don't want to receive calls from specific numbers, you may add them to your Blocked list.