Wirelessly posted (Opera/9.80 (BREW; Opera Mini/6.0.3/27.2338; U; en) Presto/2.8.119 320X240 LG VN530)
A standby means the unit goes somewhere and stands by (waits) to see if they wil get used or not.
A DR is most likely a Disposition Report number that is used in their paperwork.
Less likely, is that every doctor is assigned a number, and they look up the name associated with that number on their computer, rather than giving the doc's name out over the air. But, that's not a likely scenario. I'd go with disposition report number.