Additional information on special phone numbers

edit

The following information is not reliably sourced, but is interesting:

Ringback numbers that produced as a side effect another dialtone instead of a tone and a connected circuit seem to have been discontinued or changed from a short code to a regular-length number at a distinct point in time.[1]

A current loop is a low-impedance DC circuit (frequently powered at 24 volts) that carries audio as amplitude modulation. A loop, though, is a test number used by telco employees:

A dead battery is a now-obsolete special calling number that would connect to a normal DC-powered circuit with no modulation.[citation needed] I'm not sure they exist anymore.

There used to be numbers that would give you a connected line with an audio tone. They were used instead of tone generators or electrical buzzers to trace lines from the street to a house or within a house.[citation needed]

There are some numbers that always answer as busy.[4]

There are some numbers that temporarily disconnect phone service.[5]

Section References

edit

The above references were added on March 18, 2010. When checked on April 21, 2020, they were all dead links.--Thomprod (talk) 12:27, 21 April 2020 (UTC)Reply