Since then, 3GPP and ETSI have defined an advanced telephony architecture called IMS (IP multimedia subsystem). This provides a future-proof solution for various types of network access – 4G and 5G in mobile telephone networks, but also for fixed broadband networks, such as cable, VDSL and optical fibre networks.
In IMS architecture, several layers are identified and separated clearly from one another: media and control, but also applications and services.
The SBC, core network and media layers are responsible for controlling the call and implement multiple security levels (IPv4/IPv6 interworking, subscriber authentication) while the application servers (AS) deliver services of any kind.
Another positive side is that surveillance systems are easy to set up (lawful interception), which is specified by the Federal Network Agency (BNetzA) as part of the technical directive for the German telecommunications surveillance regulation (TR TKÜ). The ordinance requires that alternative carriers, as of a certain number of subscribers (depending on the services, e-mail, voice, fax, mobile telephony etc.), provide a surveillance system of this sort in order to answer any queries from justice departments.