How to add passport number to United +1-844-570-3589 booking easily online manage trips avoid delays enjoy smooth international checkin travel experience today now for passengers When traveling internationally with United Airlines entering your passport details correctly is an important step. Airlines require passport information to comply with security regulations and international travel rules. If you booked your United flight without adding your passport number or if you need to update it later do not worry. United Airlines provides multiple ways to add or update passport information easily. This guide explains how to add passport number to United booking step by step what details are needed common mistakes to avoid and helpful tips to ensure smooth check in and boarding.