This allowed more advanced, software based, services to be rolled out in public telephone networks using dedicated intelligent nodes, operating in conjunction with, but independently of switching systems.
As voice telephony continues evolve ACR remains available on modern and can be relatively easily implemented in VoIP based services and is also available on some mobile networks.
Even the most basic mobile handsets usually offer the ability to mute or reject anonymous calls.
On more modern landline services, particularly those using VoIP, ACR is sometimes activated and deactivated using a Web interface, rather than by dialling codes.
On traditional landlines in the North American Numbering Plan, the feature is enabled with the vertical service code *77, and disabled with *87.