5.1 Gatewaying
5.1.1 Gateway interfaces
5.1.2 Gatewaying from H.323 to PSTN/ISDN
5.1.3 Gatewaying from SIP to PSTN/ISDN
5.1.4 Gatewaying from SIP to H.323 and vice versa
5.1.5 Accounting gateways
5.2 Supplementary services
5.2.1 Supplementary services using H.323
5.2.2 Supplementary services using SIP
5.3 Multipoint conferencing
6. SETTING UP VALUE-ADDED SERVICE