Policy and Charging Rules Function (PCRF)
PCRF is a fairly new term, introduced in September 2007 when standards for the 3GPP Policy Charging Control (PCC) architecture were published. The PCRF function is part of the larger PCC architecture, which also includes the Proxy Call Session Control Function (P-CSCF) and the Policy and Charging Enforcement Function (PCEF).
Combined, the elements of the PCC provide access, resource, and quality-of-service (QoS) control.
PCRF is an important part of IMS architectures, although it is not exclusive to the 3GPP-based network in which it was certified. It works across wireless networks and can come pre-integrated in a standard IT server.
PCRF is often referred to as policy server or -- formerly -- a Policy Decision Function (PDF).
PCRF is an important element in Service Provider Information Technology (SPIT). The PCRF interfaces with the main packet gateway and takes charging enforcement decisions on its behalf. The centralized device can act as a policy decision point (PDP) for the wireless operator and gets as granular as individual subscribers.
For example, service providers can use PCRF to charge subscribers based on their volume of usage of high-bandwidth applications, charge extra for QoS guarantees, limit app usage while a user is roaming, or lower the bandwidth of wireless subscribers using heavy-bandwidth apps during peak usage times. (See The SPIT Manifesto.)
Companies that offer PCRF functionality include the major equipment vendors -- Alcatel-Lucent (NYSE: ALU), Ericsson AB (Nasdaq: ERIC), HP Inc. (NYSE: HPQ), Juniper Networks Inc. (NYSE: JNPR), and Nokia Networks -- and specialists, including Bridgewater Systems Corp. (Toronto: BWC), BroadHop Inc. , Camiant Inc. (now part of Tekelec ), Openet Telecom Ltd. , Telcordia Technologies Inc. , and Volubill .
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