public static string GetCustomerPremisePhoneNumber(FacilityDataRetrievalArgument args)
 {
     switch (args.GetFacilityType())
     {
         case FacilityType.CopperFacility: return args.GetPairAssignment().LineCardTN;
         case FacilityType.FiberFacility: return args.GetTelephoneNumber();
         default: return string.Empty;
     }
 }