Where can I check my flight reservation?

You can simply check your flight reservation via a phone number at united or delta +1-866-452-2691(Live person). Additionally, You can also check it  through an airline's website or through an online travel service like Expedia or Kayak, you'll find your reservation details in your account profile.
To check your flight reservation, you can usually do so through several methods:
 
Airline's Website or Mobile App: Most airlines have a feature on their website or mobile app where you can check your flight reservation. You'll typically need your booking reference number and your last name. Just go to the airline's website, look for the 'Manage Booking' or 'My Trips' section, and enter your details.
Email Confirmation: When you booked your flight, the airline should have sent you a confirmation email. This email usually includes your flight details and a link or instructions for how to view your reservation online.
https://feedback.azure.com/d365community/idea/f8350036-59bc-ee11-92bc-0022484c4141