I recently made a HD phone order. Reason I used phone and not online is I had a 10% off lowes coupon (from the usps movers kit) which I thought was worth a try.
I told the rep that I tried to purchase the item in store and they were willing to accept the coupon but the item was out of stock.
All he asked was if the coupon had a barcode or a code. Then he applied 10% off.