Just leave the phone in the car. If you're taking public transportation, then keep the phone with you but turn it off and don't display it. The ASC is not at a USCIS office, it's not a federal gov't installation with metal detectors and security guards.The letter for Biometrics says Phones are not permitted.
Is it that we have to leave our phones at home before going for the biometrics?
OR,
Are there any lockers in the USCIS office where we can store our phones while we are doing the biometrics?
Please let me know?