The area code 964 is actually the country of Iraq and not a US based area code. If you know someone in the military it is likely them calling you so ask anyone that fits that description if they call you from that number.
Iraq??
The country code and area code of Baghdad, Iraq is 964, 1.
The country code and area code of Amara, Iraq is 964, 43.
The country code and area code of Baquba, Iraq is 964, 25.
The country code and area code of Hillah, Iraq is 964, 30.
The country code and area code of Kirkuk, Iraq is 964, 50.
The country code and area code of Kut, Iraq is 964, 23.
The country code and area code of Najaf, Iraq is 964, 33.
The country code and area code of Nasiriya, Iraq is 964, 42.
The country code and area code of Ramadi, Iraq is 964, 24.
The country code and area code of Samawa, Iraq is 964, 37.
The country code and area code of Sulaimaniya, Iraq is 964, 53.
The country code and area code of Tkrit, Iraq is 964, 21.