The following is a list of commonly used ring patterns (or cadences to use the techno-jargon) in North America (defined in ANSI T1.401-1988 section 5.4.2). It uses a 20Hz frequency and voltage depends on distance from the central office (exchange) and will vary from 40 to 150V rms.
|Ringing (Code 1)||2 sec on, 4 sec off, repeating|
|Coded Ringing (Code 2)||1 sec on, 1 sec off, 1 sec on, 3 sec off, repeating|
|Distinctive Power ringing||Short (200 - 500ms), long (800 - 1000ms), short (200 - 500ms) in a 6 second period, repeating|
|Special ringing||two short (400 - 500ms) long (800 - 1000ms)|
REN - is Ringer Equivalence Number and defines the number of standard AT&T 500 series telephones (500 set) that can ring simultaneously. This values is normally 5 but can lie in the range 3 - 5.
The European stand ring pattern (or cadences to use the techno-jargon) is shown below (defined in ETSI prTS Interface Spec V0.0.2 (2004-11) TR41.1-05-02-010 / TR41.1.1-05-02-006 ). It uses a 25Hz (some operate at 50Hz) frequency and voltage depends on distance from the exchange) and will vary from 35 to 100V rms. This is the harmonized standard and many countries may have local variants.
|Normal Ringing||1 sec on, 4 sec off, repeating|
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