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; } }