Some AT&T customers who woke up in the wee hours Friday morning to pre-order an iPhone X got a rude awakening later that day when the carrier advised them their orders had been canceled.

AT&T's community discussion forums contain several threads in which people complain of calling customer support for more information, only to encounter call center representatives who weren't aware of the issue.

Some of the commenters say they spent hours on the phone with AT&T, sometimes getting disconnected while on hold. Other say they were told to cancel their orders and re-do them, delaying their iPhone X shipments well into December.

"I stayed up to pre-order an iPhone X, created a new account with AT&T, and was confirmed to receive the phone Nov 3," wrote a commenter on Friday who used the handle atandtwhy. "Today around noon, I received an email telling me the order was cancelled. I called into AT&T and first was told the sale department can't help, so I need to call the e-commerce department, then the e-commerce department told me I had to go to a store, then the store manager told me it's because they 'couldn't contact me for a few days', which is not possible as I did this last night, and he told me to call customer service."

Get ready: For the return of the overnight Apple Store campout

Another would-be iPhone X buyer, who used the name therunaround123, said everything appeared fine with an order after placing it. But later, after checking again online, it had been canceled:

"This morning, I checked myATT status order just to make sure that no mishaps has happened. Lo and behold, I see my order status as CANCELED. I did not receive any email regarding the cancellation and the order status provided little to no reasoning as to why my order was canceled. I called customer service to get the matter straightened out. First customer service agent spent 20 minutes trying to figure out why my order was canceled. I was placed on hold multiple times, going back and forth, ensuring that it is being looked at by a manager. After being on hold for 20 minutes, my call was ended. I waited 10-15 minutes for the customer representative to call me back, but no call back."

Julia Fleming, a former Houston resident who now lives just south of Dallas, said she ordered her iPhone X online at AT&T's website about 10 a.m. Friday morning. She confirmed with her credit card company that the sale was approved.

She thought everything was fine until she received a cancellation notice Sunday morning. It read:

Hi JULIA,

We couldn't confirm your identity with the information you gave us, so we had to cancel your order. Don't worry. If there was a hold on your card, we'll release the funds soon.

Still want to order? Visit us at an AT&T store. Be sure to bring your identification.

Thanks for choosing us,

AT&T

Fleming said she called AT&T and could not get a clear answer as to what happened.

"Nobody at AT&T knows anything about anything," Fleming said in a phone interview. "They tell me over and over again, they can't see my order, it doesn't exist.

"I want this phone, and I want it now," she said.

"If a customer has concerns or questions about their order we urge them to contact customer care so we can try to help them resolve it," the company said in an emailed statement.

Want an iPhone X? Hurry up and wait

Apple and wireless phone carriers began taking pre-orders at 2:01 a.m. on Friday for the device, which is a completely redesigned, 10th anniversary iPhone. The iPhone X will be available in stores on Nov. 3, and will ship on that date directly to those who were lucky enough to score one in the opening minutes of pre-ordering.

Analysts and sources in Apple's supply chain have said issues with components related to its Face ID feature - which uses facial recognition to unlock the phone and make digital payments - have resulted in lower yields at the factories that make the device. As a result, the phone's initial supplies were sold out, and pre-0rders made now won't be fulfilled for 5-6 weeks.

Apple had its own problems with iPhone X pre-order glitches. Customers who are enrolled in the Apple Upgrade Program had issues completing their orders in the company's Apple Store app. Apple is reportedly working with those customers to rectify the situation.

This is not the first time AT&T has canceled iPhone orders placed during the pre-order period. Customers complained of the practice during initial sales of both the iPhone 4 and iPhone 6.

[Updated at 7:26 p.m. to include AT&T's statement.]