AT&T and Microsoft have reportedly sent out emails to customers who ordered the Nokia Lumia 1520, notifying them of shipment delays.

The Nokia Lumia 1520 is the company's first phablet and the first Windows Phone phablet at the same time, and it's one of the most highly-anticipated devices of this year.

It sports a 5-inch full HD 1080p display, has a quad-core Qualcomm Snapdragon 800 processor clocked at 2.2GHz, 2GB of RAM and 16GB of internal storage capacity, expandable up to 64GB via microSD.

Other specs include a high-end 20-megapixel rear camera with Nokia's PureView technology, Carl Zeiss lens, and optical image stabilization (OIS), as well as a 1.2-megapixel front camera. The phablet is 4G LTE-enabled and supports Wi-Fi, Bluetooth 4.0, GPS, and NFC.

The Nokia Lumia 1520 is the first Windows Phone 8 phablet and comes with Microsoft's latest GDR3 update pre-installed.

The device seems to be in great demand, as some customers who ordered the Lumia 1520 from AT&T or the Microsoft Store have apparently started receiving emails informing them of slipping shipment dates.

According to a new report from Windows Phone Central, both AT&T and Microsoft have been sending out emails to customers who pre-ordered the Nokia Lumia 1520 to announce a shipping delay. The email reportedly featured only a brief notification, without mentioning when the device would actually ship.

"Because of overwhelming demand, your Nokia Lumia 1520 order is delayed in shipping. As soon as your shipping label is printed, we'll send you an email with the tracking information. You can also track your order on our site," read the message.

According to one of WP Central's readers, AT&T suggested that it should deliver the Lumia 1520 on or before Dec. 2, but the carrier is yet to confirm it.

Microsoft, meanwhile, went one step further to make amends. The company not only sent out emails apologizing for the delay, but also included a $25 promotional code that customers can use for their next purchase from the Microsoft Store.

AT&T and Microsoft retail stores reportedly have limited Nokia Lumia 1520 stock as well, so interested buyers might want to call and check for availability before heading out to buy the device.