GENERAL SS7 Network Gateway Screening SS7 messages will only be allowed to pass from one network to another@ between network elements which have been identified by both networks as a supporting element of a jointly provided service or application. A network element will be specified by OPC@ DPC@ C'gPA@ C'dPA. Other message fields applicable to screening include@ but are not limited to@ SI@ PRI@ H0-H1@ message type@ internetwork translation types@ APC@ ASSN@ and DF. Where applicable@ appropriate values are specified/assigned in national standards. Network Gateway Screening tables are configured based on the requirements and security concerns of the screening network. At the time of network interconnection@ both networks should share screening information@ to ensure no network incompatibility has been introduced by the interaction of the screening functions After interconnection is established@ screening changes which affect the terms and conditions of the interconnection agreement@ require prior notification to the affected interconnected network provider.