On April 17, 2012 NANPA added the new 566 NPA to the North American Numbering Plan. The code is assigned for Personal Communications Services along with NPAs 500, 533 and 544.
PCS codes are non geographic Service Access Codes used for so called Personal Communications. Basically, when calling a phone number starting with area code 566 (or 500, 533 and 544) your call is redirected to a real geographic phone number. PCS numbers are generally used by people or businesses who need to highly customize how their telephone system works. Calls can be redirected to national or sometimes international locations, often a message is played for callers of a PCS number (such as Press 1 for English and 2 for Spanish). PCS numbers can also be programmed to ring to certain phone numbers depending on the time when the call is placed (for example they can ring to a business phone during regular business hours and forward to a voicemail afterwards).
More resources on PCS area codes: