The National Visa Center (NVC) pre-processes all immigrant visa cases for the overseas U.S. Consulates before immigrants visas are issued. NVC handles many phone inquiries from attorneys, petitioners, applicants, etc. NVC’s main contact phone number is (603) 334-0700. When all their phone lines are being used, callers will get a busy signal. NVC has recommended through AIlA that the best times to call NVC are during the off-peak hours of 7am to 10am (EST) and 8pm to midnight (EST).