Since I've owned my first 622 (Feb '06), it has never, ever dialed out on its own. The only time it has, is by my initiation, for checking account, PPV, etc. Not nightly, weekly, monthly...not ever.
Our phone lines (4 landlines) are all managed via a PC run software. It logs ALL activity on all 4 lines. To the point, the software shows each time my 622's check for a phone line connection. Logged as: "Port X accessed Line Y....accessed dial tone Y....disconnected X." [X=622; Y=account listed phone number]
During certain operations, the software in the 622 will check for a phone line connection. Among others, accessing System Information, nightly updates/self-starts, restarts, etc.
If, during one of these checks, the software in the 622 does not access a live dial tone, the software then displays the "phone line connection" error message. (EM #006/018/078/079/080) Once this error is captured by the software, the 622 software adds additional instances it checks for a dial tone.
As example, once the registry entry is flagged to =false, each time the DVR is accessed, the error message pops up, but this is not part of routine phone connection checks. Each time it does not access a live dial tone, the error message is displayed again. This continues until the software accesses a live dial tone, which then changes the =false, to =true in the 622 registry phone connection string.
Dish has no means, currently deployed, of checking to confirm whether or not any 622 is connected to a phone line, other than annoying the user with the error message.
Quite simply, if Dish could check and confirm their receivers were connected to the account listed phone number, there would be no need for audits, with respect to dual-tuner "required" phone line connected receivers.