Contact the National Visa Center via email, phone or standard mail to obtain answers to specific questions about case status. The U.S. Citizenship and Immigration Services site allows searching case status provided there is an application receipt number to reference.
When calling or writing, be sure to provide the NVC case number, as well as the name and the date of birth of the applicant. Also provide either the petitioner's name and date of birth or the employer's name for work-related visa petitions.
Immigrants and non-immigrants who have scheduled an interview with a consular may check visa status on the U.S. Department of State website.