ZyXEL Communications omni series user manual Advanced Isdn Call Control, Call Control for DSS1

12 Advanced ISDN Call Control

Call Control for DSS1

In order to initiate a DSS1 ISDN call, two information elements are necessary:

∙Bearer Capability - indicates what kind of bearer service is desired. It is also used for compatibility checking in the addressed entity.

∙Called Party Number - provides necessary information for the telephone company Central Office (CO) to direct the call to the destination.

Other optional information elements which are pertinent to call control include:

∙High-Layer-Compatibility.

∙Low-Layer-Compatibility.

∙Calling-Party-Number.

∙Called-Party-Number.

∙Calling-Party-Subaddress.

∙Called-Party-Subaddress.

Control of Outgoing Service Indicator

The High-Layer-Compatibility and Low-Layer-Compatibility information provides a means for compatibility checking by the called party. They are transferred transparently by the ISDN network between the call originating entity (e.g. the calling user) and the addressed entity.

Advanced ISDN Call Control 79