Recommendation X.352

INTERWORKING BETWEEN PACKET SWITCHED PUBLIC DATA NETWORKS

AND PUBLIC MARITIME MOBILE SATELLITE DATA TRANSMISSION SYSTEMS

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2.	References

I.112	Vocabulary of terms for ISDNs,

I.210	Principles of telecommunication services supported by an ISDN,

I.230-Series	Bearer Services supported by an ISDN,

I.240-Series	Teleservices supported by an ISDN,

I.250-Series	Definitions and description of Supplementary Services,

I.340	ISDN connection types,

I.411	ISDN user-network interfaces - Reference configuration,

I.420	Basic user-network interface,

I.421	Primary rate user-network interface,

I.500/I.510	Definitions and general principles for ISDN interworking,

Q.700-Series	Specifications of Signalling System No. 7,

X.1	International user classes of service in public data

networks (PDNs) and ISDNs,

X.2	International data transmission services and optional user

facilities in PDNs,

X.10	Categories of access for data terminal equipment to public data	transmission services,

X.20

2.2	A public maritime mobile earth station calling another

mobile earth station

If the two public maritime mobile earth stations are in the same ocean area or are in different ocean areas covered by the same MSDSE, the MSDSE sets up the call directly to the called public maritime mobile earth station so that only one MSDSE will be involved in the call.

If the two public maritime mobile earth stations are in different ocean areas which are not both covered by the same MSDSE, the calling MSDSE will route the call in accordance with § 2.1 above.

defined within the public maritime mobile-satellite systems. Such abbreviated codes require conversion to the full international data number before the call can be forwarded from the MSDSE to a PDN.

3.	Routing of land originated calls to public maritime mobile

earth stations

Further, the first digit of the following Network Terminal Number in the public maritime mobile-satellite system is the "T" digit defined in Recommendation E.215/F.125 which is used for discrimination between different public maritime mobile-satellite systems.

A calling user can only indicate which ocean area and public maritime mobile-satellite systems (such as INMARSAT Standard A, B and C), type is addressed, and cannot select a specified MSDSE. Therefore each originating and/or transit network has normally to route data calls within one of the public maritime mobile system DNICs to a pre-determined MSDSE which serves the ocean area and system type as indicated by the DNIC and T digital according to bilateral agreement between the administration of origin and the administration operating the MSDSE. Thus, analysis of five digits of the called number is required for routing purposes.

another data number (but to the same public maritime mobile earth station), which only differs in ocean area, when a mobile earth station is absent from the ocean area indicated by the original data number. The re-routing of a call between the two ocean areas covered by the MSDSE should be carried out only once.

The condition for re-routing is that the public maritime mobile earth station is included in the list of mobile earth stations and is not barred from incoming access.

existing X-Series Recommendations and to the public maritime mobile-satellite system specifications and is therefore left for further study.

Recommendation E.215/F.125 should be barred. Such addresses are public maritime mobile earth station numbers with a T digit 0. The call should preferably be barred in the network of origin. However, the MSDSE must in any case be capable of barring such calls. (See also Recommendation X.350).

The link between the coast earth station and a public maritime mobile earth station is always a satellite link.

Hence, for a call destined to a public maritime mobile earth station, all transit exchanges should recognize from the destination DNIC of 111S that the final link is a satellite link and perform routing so that the maximum permitted transit delay from the calling user to the called user is not exceeded.