Solutons for Next Generation Networks

In IMS-based “Next Generation Networks” there are various possibilities to intercept content and related information of individual communication sessions. The optimum solution for a network operator very much depends on regulatory requirements as well as on technical properties of the network components. The diagram below shows a generalized surveillance solution for SIP-based multimedia services in an IMS network. In case other Non-SIP services are provided in addition, further interception methods may be required.

The surveillance of SIP services is done by the CSCF (Call Session Control Function) in the IMS core network. Signaling messages to or from a target ID (e.g. SIP-URI or Tel-URL) are forwarded to the LIMS system. To enable the legal interception of content data, too, the LIMS system must activate the intercept on the appropriate gateway (e.g. media gateway, session border controller) in real-time without any delay after the receipt of the call-setup signal.
The delivery of the interception data is done over standardized handover interfaces according to ETSI or ANSI standards, respectively according to national laws and regulations.

Interception in IMS-based Networks

BGF: Border Gateway Function
CSCF: Call Session Control Function
MGF: Media Gateway Function
HSS: Home Subscriber System