FUNCTIONAL ENTITIES

1. Media Gateway Controller Function

(MGC-F) a.k.a. Call Agent or Call Controller

Provides the call state machine for endpoints. Its primary role is to provide the call logic and call control signaling for one or more media gateways.

2). Call Agent Function (CA-F) and 3) Interworking Function (IW-F)

CA-F and IW-F are subsets of the MGC-F.

• CA-F exists when the MGC-F handles call control and call state maintenance. Examples of CA-F protocols and APIs include :
  • SIP, SIP-T, BICC, H.323, Q.931, Q.SIG, INAP, ISUP, TCAP, BSSAP, RANAP, MAP and CAP (mobile)
  • Open APIs (JAIN, Parlay, etc.)
• IW-F exists when the MGC-F performs signaling interaction between different signaling networks (e.g. SS7 and SIP). Examples of IW-F protocols include H.323/SIP

4). Call Routing and 5). Accounting Functions (R-F/A-F)

• R-F provides call routing information to the MGC-F, while the
• A-F :
  • collects call accounting information for billing purposes. A-F can also
  • have a broader role embodied by the common AAA functionality (authentication, authorization and accounting) in remote access networks.

6). SIP Proxy Server Function (SPS-F)

• • The most common embodiment of the R-F and A-F is as a SIP Proxy Server. For this reason, the ISC recognizes a separate SIP Proxy Server Function (SPS-F).

7). Signaling Gateway Function (SG-F) and

8). AccessGatewaySignaling Function (AGS-F)

• SG-F provides a gateway for signaling between a VoIP network and the PSTN, whether SS7/TDM- or BICC/ATM-based. For wireless mobile networks, the SG-F also provides a gateway for signaling between an IP-based mobile core network and PLMN that is based on either SS7/TDM or BICC/ATM.

The primary role of the SG-F is to encapsulate and transport PSTN (ISUP or INAP) or PLMN (MAP or CAP) signaling protocols over IP.

• AGS-F provides a gateway for signaling between a VoIP network and circuit-switched access network, whether V5- or ISDN-based.
• 9). Application Server Function (AS-F)
• The AS-F is the application execution entity. Its primary role is to provide the service logic and execution for one or more applications and/or services

10). Service Control Function (SC-F)

• SC-F exists when the AS-F controls the service logic of a function.

11). Media Gateway Function: (MG-F)

• MG-F interfaces the IP network with an access endpoint or network trunk, or a collection of endpoints and/or trunks

12. Media Server Function (MS-F)

• The MS-F provides media manipulation and treatment of a packetized media stream on behalf of any applications. Its primary role is to operate as a server that handles requests from the AS-F or MGC-F for performing media processing on packetized media streams.