Appendix D
ViewStation FX/VS 4000 User's Guide
NFAS, or Non-Facility Associated Signaling, is not supported. This
means that signaling is not supported over T1 lines that are part of
a group managed by one D-channel, and a backup D-channel is not
supported.
QSIG signaling, known as PSS1, is not supported. However, a PRI
network interface module can be connected to a PISN through a
gateway using ordinary ETSI DSS1 signaling.
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PRI Technical Notes
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