Non-Facility Associated Signalling

Non-Facility Associated Signaling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel (or D channel).wikipedia
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Primary Rate Interface

PRIprimary rateISDN30
Non-Facility Associated Signaling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel (or D channel).

Integrated Services Digital Network

ISDN ISDNISDN30
When a T1 circuit is used to carry Primary Rate ISDN one of the timeslots is used to carry the D channel. A single Primary Rate ISDN circuit is thus sometimes described as 23B + D. There are 23 bearer channels carrying voice or data, and one D channel carrying the Common Channel Signaling. North American switches such as the Lucent 5ESS, and the Nortel DMS-100 did not handle common channel signaling such as ISDN on the same line card that terminated the T1 circuit. A Primary Rate ISDN configurations uses E1 carriers, where each carrier has 32 timeslots.
Non-Facility Associated Signalling (NFAS) allows two or more PRI circuits to be controlled by a single D channel, which is sometimes called 23B+D + n*24B.

T-carrier

T1T-1T1 carrier
Non-Facility Associated Signaling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel (or D channel).

Signaling (telecommunications)

signalsignalingout-of-band signaling
Non-Facility Associated Signaling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel (or D channel).

D channel

D' channeldata (D) channel
Non-Facility Associated Signaling or NFAS is a Primary Rate Interface configuration whereby multiple T1 carriers share a signaling channel (or D channel).

Broadcast programming

television programmingtimeslotprogramming
A T1 circuit typically carries 24 individual timeslots.

Telephone call

callphone callphone calls
Each timeslot in turn carries a single telephone call.

Bearer channel

bearer
A single Primary Rate ISDN circuit is thus sometimes described as 23B + D. There are 23 bearer channels carrying voice or data, and one D channel carrying the Common Channel Signaling.

Common-channel signaling

Common Channel SignalingCommon Channel Interoffice Signalingcommon
A single Primary Rate ISDN circuit is thus sometimes described as 23B + D. There are 23 bearer channels carrying voice or data, and one D channel carrying the Common Channel Signaling.

5ESS Switching System

5ESS switch5ESS5ESS Switch project
North American switches such as the Lucent 5ESS, and the Nortel DMS-100 did not handle common channel signaling such as ISDN on the same line card that terminated the T1 circuit.

Line card

line cardsLine Replacement UnitLinecard
North American switches such as the Lucent 5ESS, and the Nortel DMS-100 did not handle common channel signaling such as ISDN on the same line card that terminated the T1 circuit.

E-carrier

E1E-1digital trunks
A Primary Rate ISDN configurations uses E1 carriers, where each carrier has 32 timeslots.

AT&T Wireless Services

McCaw CellularAT&T WirelessAT&T
With the introduction of SS7 signaling, the dialing and routing information could now be switched across the entire network (known technically as Non-Facility Associated Signalling), tying it together into a single national network.

McCaw Cellular Communications

McCaw CellularMcCaw Cellular Communications, Inc.
With the introduction of SS7 signaling, the dialing and routing information could now be switched across the entire network (known technically as Non-Facility Associated Signalling), tying it together into a single national network.