The Keystone Collections Group at the link you gave, has phone numbers with a 724 area code.
This thread is discussing a caller with an area code of 610
Well, they collect taxes for municipalities in that section of the state. The 610 area code encompasses a large area in that part of PA. It is possible that they use that area code or that they have an ofice in that section. PA went to centralized tax collectors a few year back. Keystone is the tax collector for Northampton County, which is in the 610 area code. If it is Keystone Collections then it would be out of the LC Sheriff's area.
Collect Taxes from whom? A good number of complaints under that name. Is Keystone still associated with Forward Movement Recovery? As of about a month ago it sure looks like it.