The actual status of the Sonet interface. Interface is
Up if it is administratively in service and there are no
line failures or hardware failures. Interface is Down if
it is administratively in service and there are line
failures or hardware failures, or if it is administratively
out of service. Interface is DryingUp if it is administratively
out of service and is drying up (no new calls, still carrying
in-progress calls). OTHER VALUES ARE NO LONGER SUPPORTED