Area code 312 is the telephone area code for downtown Chicago, which includes the Chicago Loop and its immediate environs.
 The plan area is completely surrounded by area code 773, which serves the rest of Chicago.
 Both area codes are overlaid with area code 872.
 312 is an enclave area code, similar to area code 213 in Los Angeles, area code 514 in Montreal and area code 210 in San Antonio.
 It is roughly bounded by North Avenue on the north, Western Avenue on the west, and 35th Street on the south, with Lake Michigan to the east.
 In terms of geographic area covered, 312 is one of the smallest area codes in the nation, encompassing only a few square miles.
Area code 619 is a California telephone area code that was split from 714 on November 5, 1982.
 This area code currently covers the southern half of the city of San Diego and its eastern and southern suburbs.
 Area code 619 was the first new area code in the NANP since area code 804 was split off from 703 in 1973, and the second area code added since 1966.
North American area code 806 is a state of Texas telephone area code for numbers in the Texas Panhandle and South Plains, including the cities of Amarillo and Lubbock.
 806 was created as a flash-cut sometime during 1957, but available databases do not indicate from which area code it was split, as all original area codes were created in October 1947.
 Based on proximity, however, it was probably split from the 915 area code.
 In a message posted to the Telecom Digest mailing list and newsgroup comp.dcom.telecom, Carl Moore reports that this area code was created mostly in part from area code 915 as well as a small part from area code 817.
Area code 284 is the local telephone area code of the British Virgin Islands (BVI).
 The 284 area code was created during a split from the original (809) area code which began permissive dialing on 1 October 1997 and ended 30 September 1998.
Area code 664 in the North American Numbering Plan covers Montserrat, a tiny British Overseas Territory in the Caribbean.
 The 664 telephone area code, standing for "MNI," was created during a split from the original 809 area code, which began permissive dialing 1 July 1996 and ended 1 June 1997.
The politics of Gibraltar takes place within a framework of a parliamentary representative democratic British Overseas Territory, whereby the Monarch of the United Kingdom is the constitutional head of state represented by the Governor of Gibraltar.
 The Chief Minister of Gibraltar is the head of Government.
 As a British Overseas Territory, the Government of Gibraltar is not subordinate to the Government of the United Kingdom.
 The British Government, however, is responsible for defence and external affairs but Gibraltar has full internal self-government under its 2006 Constitution.
 Gibraltar is represented in the European Union, having been the only British Overseas Territory to have joined the European Economic Community under the British Treaty of Accession (1973).
Area code 860 is a telephone area code, overlaid by area code 959, that covers most of Connecticut, except its southwest, which uses area codes 203 and 475.
 Area code 959 was originally announced in August 1999, to overlay area code 860 when the 860 code nears exhaustion, starting in August 2014.
 Effective November 14, 2009, all calls within Connecticut must be dialed with 10 digits beginning with the area code, including calls involving two numbers using the same area code.
Telephone area code 708 covers western and southern Cook County and eastern and southern Will County in the state of Illinois, USA.
 Area code 708 was split off from area code 312 on November 11, 1989, and once covered almost all of the suburbs of Chicago.
 In 1996, area code 847 and area code 630 were broken off from 708.
 Area code 464 is being reserved as an overlay area code for 708 to provide additional numbering options for this area.
Area code 909 is a California telephone area code that covers far eastern Los Angeles County and southwestern San Bernardino County.
 The 909 area code was split from area code 714 on November 14, 1992.
 By August 1993 use of the new area code became mandatory.
 Western Riverside County was split off from 909 into area code 951 on July 17, 2004.
 Originally on that same date, the area retaining the 909 area code was to be overlaid by a new area code 752.
 However, this overlay plan was shelved prior to the 909/951 split, and area code 752 was returned to the NANPA numbering pool to be assigned at a later date.
 909 still covers small portions of Corona, Riverside, and Moreno Valley, which are in Riverside County.
The British Virgin Islands (BVI), officially simply "Virgin Islands", are a British Overseas Territory in the Caribbean, to the east of Puerto Rico.
 The islands are geographically part of the Virgin Islands archipelago and are located in the Leeward Islands of the Lesser Antilles.

Question: What is the area code of the British Overseas Territory in the Caribbean?
Answer: 284