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Ever noticed that phone numbers given in American movies and TV shows invariably start with the 555 prefix? Ever wondered why 555 and not something else?

The answer lies 30 years ago or more when the use of exchange names as part of the telephone number was still popular in the USA. Dials had letters as well as numbers and the first 3 letters of the exchange name were dialled followed by numbers. An example might be CENtral 78978. You dialled CEN 78978 or, using all numbers, 236 78978.

It so happened that 5 on the dial corresponded with J K and L and you can’t make any English place names using any combination of J, K and L as the first 3 letters. So the 555 code was allocated to service levels such as Directory Assistance, Operator, Repair Service, etc.

Due to the "low fill" of the 555 code, Hollywood was encouraged to quote 555 numbers in their productions to prevent real subscribers being harassed by members of the public trying out the numbers quoted on the screen. Generic and satirical advertisements and commercials often used 555 numbers. In the early days of exchange names the prefix KLondike-5 was used as this exchange did not exist.

Of course, there was a 555 code in each city (or each locality with its own area code). Therefore there were a lot of 555 codes around the USA being under-used. And with the advent of long distance dialling, anyone could call anywhere by adding an area code to the 555 number.

Now the 555 code in the USA is starting to fill up with various Service Providers demanding numbers in this range. The commonly used 555-1212 for Directory Assistance is being joined by a wide range of numbers for a wide range of uses. Only 555-0100 to 555 0199 (100 numbers) has been set aside by Bellcore for Hollywood and entertainment fiction. Modern movies should only use this range - we shall have to watch and see.

In Australia there is no special level for movies and TV. Any number quoted in the media may be a real subscriber in some city or town. The chances are that if someone rings a ‘fictitious’ number quoted on the screen, they will get a real subscriber.

The 555 code is alive and well and in use in the Balmain area of Sydney and somewhere in the suburbs of Melbourne but not in the other capitals. It would be that 555 is valid in many country areas being a prefix of 55 plus the thousand digit of 5 (e.g. 55 5XXX). But then, with the recent re-numbering, everything has changed. 555 has become 9555 in Sydney and Melbourne and in the country, there are 2 new digits ahead of the 55.

From article by Mark Cuccia in Telecom Heritage, issue 27

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