Hello, and welcome!
I'm sorry to hear that you left your phone at the security checkpoint at IAH Houston, yesterday. You can call or email the TSA lost and found for IAH, here:
If you believe you have lost your personal item(s) at the Transportation Security Administration (TSA) security checkpoint, please contact the TSA Lost and Found at(###) ###-####or email *****@******.***
If you left the phone at Houston, it doesn't make sense to contact United in Atlanta (your destination); it's not a baggage claim, it's a 'lost at a TSA security checkpoint' claim.
Call that number above, or email and then fill out the TSA claim forms for the lost phone to the TSA.
I hope you get your phone back!
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