The North American Numbering Plan Administration (NANPA) is in charge of allocating the phone number address space fo the U.S.  There are reserved phone numbers for fictitious use, just like there are reserved IP addresses (RFC5737).  For example, numbers 555-0100 through 555-0199 are reserved and can be found on the NANPA website at [more]

In addition, here are a copule of other countries for international numbers:

For Austrailia:

For UK: