ringdown

Ringdown: In telephony, a method of signaling an operator in which telephone ringing current is sent over the line to operate a lamp and cause the drop of a self-locking relay. Note 1: Ringdown (a) is used in manual operation, as distinguished from dialing, (b) uses a continuous or pulsed ac signal transmitted over the line, and (c) may be used with or without a switchboard. Note 2: The term "ringdown" originated in magneto telephone signaling in which cranking the magneto in a telephone set would not only "ring" its bell but also cause a lever to fall "down" at the central office switchboard. Source: from Federal Standard 1037C and from MIL-STD-188

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reflective array antenna
reflectivity
refracted ray
refractive index contrast
reframing time
regeneration
relative transmission level
release time
reliability
remote access
remote call forwarding

remote operations service element protocol
repeater
repeating coil
reproduction speed
reradiation
resolution
resonance
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restoration

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ringaround
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