What is called when you just use the first letters of words like F.B.I or C.I.A?

Technically, FBI and CIA are initialisms. It's only if you can pronounce the word (like RADAR) that it's an acronym. Dictionaries usually give those definitions, but nowdays most people call them all acronyms.

Actually, telling them is good enough. My best friend is a manager for a collection agency and this is what she says: "you need to tell them that according to the FDCPA (Fair Debt Collection Practices Act) you only have to give them one time verbal request not to call you at work anymore and if they still do it, that you are going to report them to the Attorney General's office. And then back it up in writing. And if they still continue to call you at work, consult with an attorney. According to the FDCPA, a 3rd party collection agency cannot contact a consumer at any known time or place where it inconveniences the consumer (in this instance, at work). This also includes before 8am and after 9pm, 7 days a week." Hope this helps!

When you take the first letters of somethings name to represent it like in FBI and CIA it's called an acronym.

It's called an acronym:

"Acronyms and initialisms are abbreviations that are formed using the initial components in a phrase or name. These components may be individual letters (as in CEO) or parts of words (as in Benelux or Delmarva)." -Wikipedia

Hope that helps.

Using First Letters Of Words

A acronym.

it is called acronym

acronym

acronym

abreviations or acronyms