What is a (Local Exchange) Prefix?
The first three digits of a seven digit phone number in the North American
Numbering Plan are called the "prefix" or "exchange". In some areas, you
are limited to a small set of prefixes determined by your physical location.
This is because -- in the old days -- the telephone network used these first
three digits to connect an incoming phone call to the right "central office"
where other electrical hardware would then interpret the remaining four
digits. Basically, this type of network layout, a hierarchy, made telephone
networks cheaper to build and maintain.
Even though most modern telephone networks being build and upgraded today
are so flexible that such restrictions are no longer necessary, telephone
companies continue to use the old conventions. In future, you will be
able to get any prefix in just about any area code, no matter where the
actual telephone is located (as is already a the case with internet based
Which is the best prefix to have?
When it comes to vanity numbers (phone number mnemonics), some prefixes
are better than others. This is because different three-digit combinations
will be more or less likely to represent the first three letters of a word.
For instance, 18 words start with the letters associtated with the prefix "592"
and 353 words with "92", while there no words in the english language starting
with the letters for "555" and only 23 with "55". You can use our Prefix Comparison Tool to compare the vanity number potential
for local prefixes.
In general, if you are trying to get a phone number with good
vanity phone number potential, prefixes containing 1's and 0's should be
avoided, as should prefixes with consiting only of 7's and 5's, since these
numbers only map to consonants.
If you stuck with a certain prefix, you may also be able to ask
the telco's customer service representative if certain numbers are available.
Use our Prefix Search to get a
list of words for your prefix.