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NAM	Network applications management. The ICM in a two-tier service bureau architecture that receives route requests from the carrier network and forwards them to a customer ICM.
NAPTR	Naming-authority pointer. Algorithm for converting an E.164 number (such as 14085551212) into a fully qualified domain name (such as 2.1.2.1.5.5.5.5.8.0.4.1.e164.arpa).
NAS	Network access server. Server that connects asynchronous devices to a LAN or WAN through network and terminal-emulation software. Performs both synchronous and asynchronous routing by means of supported protocols.
NCP	1. Network control point. Process within the AT&T signaling network that sends routing requests to a customer routing point such as the network-interface controller (NIC) within the ICM. 2. Network Control Program. SNA program that routes and controls the flow of data between a communications controller (in which it resides) and other network resources. 3. Network Control Protocol. Series of protocols for establishing and configuring different network layer protocols, such as for AppleTalk over PPP. See also PPP.
NCS	Network-based call signaling for residential gateways.
never-busy fax	See fax rollover.
NFAS	Nonfacility-Associated Signaling. ISDN service that allows a single D channel to control multiple PRI interfaces, thus freeing one B channel on each interface to carry other traffic.
NFAS group	PRI channel group (the group of interfaces) that is under control of a single D channel. Can include all of the ISDN channels on multiple T1 controllers.
NFAS member	PRI interface in an NFAS group. For example, an NFAS group might include serial interfaces 1/0:23, 1/1:23, and 2/0:23 if T1 controllers 1/0, 1/1, and 2/0 are configured for NFAS.
night service	Service that provides, during specified hours, notification to designated phones that a particular extension on a different phone is ringing.
NLP	Nonlinear processor.
NM	Network module. Hardware component that stores application software.
NMS	Network management system. System responsible for managing at least part of a network. Communicates with agents to help keep track of network statistics and resources.
node	H.323 entity that uses RAS to communicate with the gatekeeper, for example, an endpoint such as a terminal, proxy, or gateway.
NOTIFY message	NOTIFY message. Message that reports when certain events, such as DTMF events, occur in a SIP system.
NSE	Named signaling (or service) event. Format of RTP packets used for applications such as modem relay and fax relay. NSEs have different payload values than NTEs. See also NTE.
NSF	1. Network-specific facilities. 2. Nonstandard facilities. Capabilities that fax manufacturers have built into fax machines to distinguish their products from others. Also a message sent by a called fax machine during capabilities exchange to advise the calling device of nonstandard facilities that are available on the called fax machine.
NSS message	Nonstandard-Facilities Setup message. Message sent by a calling fax machine during capabilities exchange in response to an NSF message. The NSS message selects the extra reception parameters from the NSF message that the calling fax machine wants to use for this call.
NT	Network termination. Device that provides the interface between customer-premises equipment and central-office switching equipment.
NTE	Named telephony event. Event such as DTMF digits that must be encoded and transported in an RTP packet. Not all gateways use protocols capable of performing this encoding (SCCP, for instance, has no such capability). See also NSE.
NTP	Network Time (or Transfer) Protocol. Protocol for synchronizing a router to a single clock on the network, known as the clock master.