He probably has a cellphone and kept the number when he moved from the San Francisco Bay Area to San Diego.
There is no area code 619 in Mexico.However, U.S. area code +1 619 serves San Diego, California.(The plus sign means "insert your international access prefix here." From a GSM mobile phone, you can enter the number in full international format, starting with the plus sign. The most common prefix is 00, but Japan uses 010, Australia uses 0011, and many other countries use different prefixes.)
Santa Monica is in area code 310 and overlay area code 424.
King's Norton uses the Birmingham area code, 0121.
Pretty much any mobile phone service provider in the Toronto area will give you a number in area code 647, or the even newer overlay code, 437.
Wyoming (WY) uses area code 307.
Milton Keynes uses the area code 01908.
Godalming uses area code 01483. Dialled from overseas, this would be +44 1483
it has to get uses to its area (6 months)
New Rochelle, and all of Westchester County, uses area code +1 914.
Pompano Beach is in Broward County, Florida, which uses telephone area code 954 with overlay code 754.
The area code 516 is a US area code used in New York. The area code 516 is specifically used in Long Island, New York, in the Nassau county. The area code applies to both cell phones and landlines in the area.
Montserrat is in the same +1 country code as the USA and Canada. It uses area code 664, followed by regular seven-digit numbers.