It was 11:30 in the morning on Black Friday, and the lunch crush was booming.  Suddenly the noise level inside the restaurant grew and the Drive-Thru crew was nervously trying to recover from some sort of glitch. As the volume increased we realized it was coming from outside:  aggravated Drive-Thru customers, unattended, were honking their car horns.  The heart of our Drive-Thru operation had failed: communications were down.  As the line grew, the noise intensified and everyone's nerves were jangled, including those of dine-in customers.  The installer technician was immediately called, but they couldn't come for a couple of hours.  Meanwhile, our store manager came out of the back room with a large red box and pulled out the back-up system we needed.  Within minutes, the 911 Emergency System, our reliable backup vehicle detector, speaker and receiver was operating flawlessly.  Having the 911 Emergency System on site saved the day and quite a bit of revenue at this critical holiday time. As it turned out, the technician had to order a part that could not be received until the following morning. Having a back-up system on hand is like having a defibrillator on site: It gave the "heart" of our communication system a good jolt and put us back in the pulse of holiday meal-time activity all weekend.  Holiday or not, what a relief to have it on hand in an emergency situation.