You want to fly United Airlines, but you don't know when to book. United Airlines has flights that are cheap. They also have great customer service. It's easy to find great deals on United Airlines and other airlines. At Fond Travels, the number for United Airlines customer service is +1-571-389-6426. visit - https://www.fondtravels.com/blog/travel-tips/best-day-to-book-a-flight-on-united-airlines