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E1IsdnDSS1PrimaryRateTEStandards Basic and primary rate ISDN interfaces are according to ETSI and ITU-T standards. ISDN Primary Rate (PRI), the types of interfaces supported are:
Layers and Options The physical layer of primary ISDN access in Telesis systems is an E1 (ITU-T G.703) interface. 120 ohm balanced terminations are supported on any E1. The line code is HDB3 or AMI programmable. CRC4 may be enabled or disabled. Several parameters in ISDN messages are programmable. Those are:
ISDN Supplementary Services The following ISDN supplementary services are supported:
Route and Routeset Configuration In a Telesis system, each basic and/or primary ISDN access may have its own route number. It is possible to define up to 128 distinct routes. For primary access, a given route to a particular destination and its accompanying routes are grouped in a routeset. Each route in a routeset has a priority order. Routing to the next priority alternate route is possible in the event that a route becomes unavailable. Furthermore, it is possible to define which release causes stated in Layer-3 messages will lead to the alternate routes being used. For accessing PRI, the channel selection type is programmable as ascending, descending, or cyclic. Disabling outgoing calls from certain channels also yields fractional E1 use. Routing A Telesis system may realize routing calls from ISDN interfaces according to:
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