An IBCF provides application specific functions at the SIP/SDP protocol layer in order to perform interconnection
between two operator domains. It enables communication between IPv6 and IPv4 SIP applications. network topology
hiding, controlling transport plane functions, screening of SIP signalling information, selecting the appropriate
signalling interconnect and generation of charging data records. Details are described in TS 23.228.
Interrogating-CSCF (I-CSCF) is the contact point within an operator's network for all connections destined to a user of
that network operator, or a roaming user currently located within that network operator's service area.
The IM subsystem comprises all CN elements for provision of IP multimedia services comprising audio, video, text,
chat, etc. and a combination of them delivered over the PS domain. The entities related to IMS are CSCF, MGCF,
MRF, etc. as defined in the stage 2 of the IM subsystem TS 23.228.
See TS 22.228 for some service examples of IMS.
An IMS-MGW may terminate bearer channels from a switched circuit network and media streams from a packet network
(e.g., RTP streams in an IP network). The IMS-MGW may support media conversion, bearer control and payload
processing (e.g. codec, echo canceller, conference bridge), it:
Interacts with the MGCF for resource control.
Owns and handles resources such as echo cancellers etc.
May need to have Codecs.
The IMS-MGW will be provisioned with the necessary resources for supporting UMTS/GSM transport media. Further
tailoring (i.e. packages) of the H.248 may be required to support additional Codecs and framing protocols, etc
The IP Short Message Gateway function is used for two functions: to deliver SMS messages over the IP network and to
provide interworking between SMS users and Instant Messaging users. The interworking function translates between
MAP or Diameter based signalling and SIP signalling to convey messages and responses between the two systems.
Both functions are described in TS 23.204.
IM Services Identity Module (ISIM) application residing on the
If the Terminal wants to engage in IMS operation, then after UICC activation, the Terminal shall
select an ISIM application, if an ISIM application is listed in the EFDIR file, using the SELECT by DF name as defined
in TS 31.101.
After a successful ISIM application selection, the selected ISIM (AID) is stored on the UICC. This application is
referred to as the last selected ISIM application.
The Interworking Function (IWF) is a functional entity associated with the MSC. The IWF provides the functionality
necessary to allow interworking between a PLMN and the fixed networks (ISDN, PSTN and PDNs). The functions of
the IWF depend on the services and the type of fixed network.
The IWF is required to convert the protocols used in the
PLMN to those used in the appropriate fixed network. The IWF may have no functionality where the service
implementation in the PLMN is directly compatible with that at the fixed network. The interworking functions are
described in TS 29.007.