Wrong number

A misdialed call or wrong number is a telephone call to an incorrect telephone number. This may occur because the number has been physically misdialled, the number is simply incorrect, or because the area code or ownership of the number has changed. In North America, toll-free numbers are a frequent source of wrong numbers because they often have a history of prior ownership. In the United Kingdom, many misdialled calls have been due to public confusion over the dialling codes for some areas.

The recipient of a wrong number is usually unknown to the caller. This aspect has been used in social science experiments designed to study the willingness of people to help strangers, and the extent to which this is affected by characteristics such as race. This experimental method is known as the "wrong-number technique".

Proper telephone etiquette recommends that the wrongly dialled party politely inform the caller of that fact, and also that the caller apologize rather than simply hanging up. Often the two parties will confirm whether or not the intended number is indeed the number that was reached (e.g. "Is this 555-0184?") before ending the call. It is widely considered "dangerous" for the called party to disclose their phone number — rather it is considered more prudent to require the calling party to state which number he dialled and for the called party to simply confirm whether or not that is his number.

On a landline, wrong numbers incur no toll for the recipient but do represent the annoyance of answering an unwanted call. This may be problematic for shift workers who are asleep during the day. On cellphones in countries where mobile plans charge for incoming calls, a wrong number may cost the subscriber one or more minutes.

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Wikipedia