https://www.theverge.com/2017/11/3/16604392/iphone-x-activation-issues-att-verizon-apple

A number of iPhone X owners on Twitter have reported having issues activating their new phones. The issue seems to be affecting some AT&T and Verizon users in the last few hours as they try to get service on Apple’s $1,000 phone. When users try to activate the device, a message pops up saying, “The activation server is temporarily unavailable.”

Hey @Apple not sure if you heard, but the #iPhoneX came out today. Maybe fix the activation server? Now, please. pic.twitter.com/nh6Vgvc4Bj