r incoming calls from legacy networks; perform protocol conversion between the legacy (e.g. ISUP, R1/R2 etc.) and the ROO network call control protocols; assume reception out of band information for forwarding to the CSCF/MGW. 9.3.6 Media Gateway Function (MGW) The MGW serves as the PSTN/PLMN transport termination point for a defined network and UTRAN interfaces with the CN over Iu. It may terminate bearer channels from a switched circuit network (i.e. DSOs) and media streams from a packet network (e.g. RTP streams in an IP network). Over Iu, the MGW may support media conversion, bearer control and payload processing (e.g. codec, echo canceller, conference bridge) for support of different Iu options for CS services, AAL2/ATM based as well as RTP/UDP/IP based. The main functions include: interaction with MGCF, MSC server and GMSC server for resource control; ownership and resources handling, e.g. echo cancellers etc.; ownership of codecs. Towards IP Based Networks The MGW will have the necessary resources to support UMTS/GSM transport media. It will also have customized H.248 packages to support additional codecs and framing protocols, etc. from other networks besides GSM and UMTS. The MGW bearer control and payload processing capabilities will also support mobile specific functions, e.g. SRNS relocation/handover and anchoring through H.248 protocol enabling. The follow- ing principles apply to the CS-MGW resources: it shall not be necessary to have the CS-MGW co-located with the MSC server; the CS-MGW resources need not be associated with any particular MSC server1; it shall be possible for any MSC server to request resources of any CS-MGW in the network1: it shall be possible for an RNC to connect to the CS-MGW indicated by the MSC inserver. 9.3.7 Multimedia Resource Function (MRF) The MRF performs: multiparty call and multimedia conferencing functions, i.e. would have the same functions as a MCU in an H.323 network; performs bearer control (with GGSN and MGW) in cases of multiparty/multimedia conferencing; comm