1. Of a device, the mathematical function that describes the output waveform that results when the input is excited by a unit impulse.
2. The waveform that results at the output of a device when the input is excited by a unit impulse.

IP Multimedia Subsystem

Abbreviation for intelligent network.

A UPT (Universal Personal Telecommunications) call type which permits a UPT user to have calls to his/her UPT number routed to the terminal specified by the user. [After T
1. Rpt41-1995]

A feature by which incoming calls are presented at the terminal address registered previously by in-call registration. This feature is invoked when originating parties or others call the UPT (Universal Personal Telecommunications service) user. [T1.701-1994]

A code or block for which local routing information has been input to the LERG Routing Guide and the carrier has begun to activate and assign numbers within the NXX code or NXX-X block to end users (FCC 00-104, ¶240).

Using or involving the information digit time slots of a DS1 frame; i.e., bit assignments of a frame exclusive of the framing bit. [T1 Gloss ‘90] [T1.403-1989]

Control effected by sending control information over the same channel as the one used to send data.

For multichannel equipment, the ratio of (a) the mean noise power measured in any channel, with all channels loaded with white noise, to (b) the mean noise power measured in the same channel, with all channels but the measured channel loaded with white noise.

Signaling that uses frequencies or time slots within the bandwidth or data stream occupied by the information channel.