Ringback Guide, Meaning , Facts, Information and Description
Ringback is a test used by many phone companies to quickly determine whether or not a new phoneline is working correctly and the phone number is routing properly.Typically it works by calling a "ringback number" and then hanging up. Often the ringback number plays a low frequency tone into the line to indicate that it's working, at which point the technician "flashes" the line (hangs up very briefly) to indicate they want a ringback. This makes the ringback play a higher tone to indicate it is working, and then the technician hangs up. The phone will then ring, answering only with a tone if picked up.
The tone is added so that telephone subscribers will not be able to easily use the ringback system as an "intercom," to call other extensions of their own phone line by simply initiating a ringback test and waiting for the phone to stop ringing (so as to know when the other person has answered).
137(Normal Tone)
This is an Article on Ringback. Page Contains Information, Facts Details or Explanation Guide About Ringback New Zealand Telecom
In New Zealand, you just need to call the number, wait for the tone, then hang up.
136(Continuous Tone)Telefónica de España landline system
In some areas of Spain, users connected to Telefónica de España landline system can obtain a ringback by dialling 020 and waiting for continuous tone.