hange charging correlation information between IMS and GPRS network PDF and P-CSCF It is used to exchange information related with policy decisions between the PDF and P-CSCF. CSCF and AS IMS Service Control Interface (ISC) is used to provide services residing in an AS (external and home network) RNS and CN It is used between RNS (Radio Network Subsystem and CN (Core Network). IMS-ALG and NA(P)T-PT It is used between IMS-ALG and NA(P)T-PT. AS and GMLC It is used to ensure that the privacy requirements of SIP application servers are met. To IPv6 services It is used by MRFP for the control of the bearer traffic. MGCF and CSCF It is responsible for converting ISUP signaling to SIP. It allows MGCF to forward incoming session signaling from the CS domain to the I-CSCF. CSCF and BGCF It is used to exchange messages between S-CSCF and BGCF. BGCF and MGCF It is used to exchange messages between BGCF and MGCF in the same IMS network. BGCFs It is used to exchange messages between BGCFs in different IMS networks. CSCF and IP networks It is used to exchange messages between IMS and external IP networks. MGCF and IMS-MGW The Mn interface controls the user plane between IP access and IMS-MGW (Mb reference point). MRFC and MRFP It is used to exchanges messages between MRFC and MRFP. CSCF and MRFC It is used to exchange messages between S-CSCF and MRFC. CSCFs It is used to exchange messages between CSCFs. CSCF and IMS-ALG It allows S-CSCF/I-CSCF to communicate with an IMS ALG to provide inter-working with networks that use a different IP version. AS and HSS It is used to exchange information between Application Server and IM-SSF and HSS It is used to exchange information between IMS-SSF (Service Switching Function) and HSS. UE and AS It enables UE to manage information to relate his/her services. Next Generation Mobile Communications Ecosystem Network Subcription Policy Policy Application Application Rules Server Server Databases 8/OSA-API 12/SC Breakout Network OSA Service Gateway Management Capability Control Server Layer/OSS 