If you suspect someone is in the United States illegally, you can report your suspicions to either U.S. Immigration and Customs Enforcement or the U.S. Border Patrol sector where the individual is located. The agency will ask for such information as the person's name and where he lives or works. If you wish to stay anonymous, simply don't provide your name, either on the phone or on the tip form you submit online.
Submitting Tips to ICE
ICE enforces U.S. immigration laws. It identifies, detains and deports undocumented immigrants, prioritizing those who are fugitives, pose a threat to national security, are convicted criminals or recently crossed the border. To make a report with ICE from the United States, Canada or Mexico, call 866-347-2423. If you're making the report from a different location, call 802-872-6199. You can also submit your tip online at ICE's website.
Submitting Tips to the USBP
The U.S. Border Patrol is responsible for detecting and preventing persons from illegally entering the United States. This is done by patrolling the nation's land and coastal borders, preventing the illegal trafficking of both contraband and people. If you want to report suspected illegal activity or undocumented persons at or near the nation's border, contact the USBP sector in the area. The U.S. Customs and Border Protection website provides links to its sector stations online. When you click on a link, you will find a station's address and phone numbers. You can also submit your tip to the USBP by calling their hotline at 800-232-5378.