Area code 664 in a telephone area code in the North American Numbering Plan (NANP) for Montserrat, a British Overseas Territory in the Caribbean.
The digits of the area code translate to MNI in the alphanumeric mapping on telephone dials.
A call from another North American Numbering Plan country (such as the United States or Canada) requires dialing the long-distance access code (1), the NPA code, and the seven-digit telephone number.
At one time the small island of Montserrat used only four-digit telephone numbers internally, as the first three digits after the former 809 area code were the same for everyone (491).
You can help Wikipedia by expanding it.This article related to a telephone area code is a stub.