Editing Ringback number (section)

== Examples ==
Some ringback numbers are local or regional in scope, while others are larger in scope. Every telephone company determines its own ringback numbers for each individual central office. Under the [[North American Numbering Plan]], most North American area codes reserve telephone numbers beginning with ''958'' and ''959'' for internal testing. Some companies also reserve ''999'' for test exchanges. Numbers within these test exchange block ranges are used for various types of local and long-distance testing; generally, this block includes a '''ringback number''' (to test the ringer when installing [[telephone]] sets) and a [[loop around]] (which connects a call to another inbound call to the same or another test number). Ringback numbers may appear in the ''958'' exchange, but there is no requirement that they reside there.

Some large telephone companies have [[toll-free number]]s set up for ringback. In most cases, these numbers remain undisclosed to prevent abuse. Some companies change their ringback number every month to maintain secrecy. Some carriers (such as [[Bell Canada]]) have been known to disable all [[payphone]] calls to 958 or 959 test lines.

4101 was formerly valid on some mechanical switching systems to allow a call to the other party on a two-party line. Like 4104 (repair, long replaced by 611 in most cities), it was once a standard number in many areas but has disappeared as this equipment (and the [[party line (telephony)|party line]] service itself) has been decommissioned.

In the 1970s and early 1980s, 1199011 was a number that when called would result in another dial tone.  Afterwards, if the phone was hung up and then quickly picked up again in less than approximately 1/2 second (ie: a [[hook flash]]), a steady tone would then be heard (different from a regular dial tone).  Hanging up the phone after this would result in a ring back.  When the ring back was answered, the ring back process could be repeated by hanging up and lifting up the phone quickly again, and then hanging up.

Most other numbers listed for ringback are specific to one exchange or one telco; available lists tend to be outdated and unreliable. Many former test numbers (such as 320 and 999 in Bell Canada territory) have been reclaimed for use as standard landline or mobile exchange prefixes, with the test codes moved (usually) to the 958 exchange.