Freezing rain should be reported to the National Weather Service at all times, regardless of accumulation.  Ice accumulation is reported to the nearest tenth of an inch, and is taken radially (e.g. one side of a branch or wire).  Take a measurement in an unprotected area away from structures and trees.  If measuring ice on a tree, avoid lower branches which get sheltered from higher limbs.  Sometimes wind-driven rain will cause significant ice buildup on one side of an object with lesser accumulation on other sides.  In this case report the higher amount.  Also report any damage to trees or power lines, and give the approximate size of any broken tree limbs.  Do not include sleet accumulation when reporting ice.  Sleet is considered snowfall, and should be included with snow accumulation.