Several times in the past few weeks I've heard discussions regarding what is required for legal station identification by US Amateur Radio operators. I always thought that I knew the legal requirement and I'll bet most other Hams believe they know as well. But there seem to be a variety of opinions including a common belief that you must identify your own station as well as the station with which you are in contact every 10 minutes.
The ARRL maintains an online copy of FCC Part 97--the rules that govern the Amateur Radio Service. Section 97.119 Station Identification has the details of interest here. This excerpt at the beginning sums it up nicely...
(a) Each amateur station, except a space station or telecommand station, must transmit its assigned call sign on its transmitting channel at the end of each communication, and at least every ten minutes during a communication, for the purpose of clearly making the source of the transmissions from the station known to those receiving the transmissions. No station may transmit unidentified communications or signals, or transmit as the station call sign, any call sign not authorized to the station.
Note that in the preceding and in fact in the entirety of 97.119 that there is no mention of any requirement to identify the station with whom you are in QSO with. You are only responsible for identifying your own station once every 10 minutes and at the end of the communication.
Now it is very common in CW and other digital modes to hear people identify both stations at the beginning and end of every transmission. Legally this doesn't appear to be necessary however as a matter of good operating procedure it seems that it would be common courtesy to mention the other station specifically frequently since non voice modes can easily all "sound" the same. This allows both operators to stay in the same conversation and not inadvertently wander off.
I was always taught to use both call signs once in every CW transmission and both call signs for the once every 10 minute requirement on phone. What do you think is good procedure?
