The link to the FAQ at the bottom looks to be an internal only link:

http://www-author.cisco.com/c/en/us/products/collateral/routers/4000-series-integrated-services-routers-isr/qa_c67-728261.html

The 4221 looks like it has good use cases but it's quite odd that it doesn't have a USB serial port. Is Cisco abandoning the concept of USB-Serial and going back to RJ45 consoles again?