Do a show controller t1 - check for items based on flow chart at link below:

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00800a5f40.shtml

If there is a remote alarm - it implies the far end is at fault i.e. your provider. Another test to ensure its not a HW issue is to create a hardware loopback plug and check if the controller comes up if loopback cable is in - if it comes up then you know its not the UC520

http://www.cisco.com/en/US/tech/tk713/tk628/technologies_tech_note09186a00800a7599.shtml