7/19/04

Push to talk -- what to do?

Recently, I ranted about PTT technology on mobile phones. (Find it here.) Someone named Saso called me to task:
... it seems to me that you left a bit too much as an exercise for the reader. What am I talking about? The Push to talk service provides people with a perfect eavesdropping device. TSCM industry will love this one. All mobiles should be already banned from meeting rooms, but since they're not, often they get used as one party's way to let more people in to the discussion as there's physically present parties. For that to work in the old days, you'd need an accomplice on the inside or a physical access to the room. Now, all you need is the name of the one of the parties attending a strictly confidential meeting and their direct call number. And you don't even have to be anywhere near the meeting place, like in the old times. Is the handset beeping loud enough when you establish a connection? Loud enough not to be drowned in the average office noise? Street noise?
(As a funny coincidence, someone just walked by the office I am sitting in today, talking on this annoying walkie-talkie mobile phone. :-) Or maybe they are really ubiquitous.)

These are all good points, and yes I should have made some observations and recommendations instead of just grumping. First, the open questions to answer:
  • Is it possible to turn off this feature? Almost certainly, "yes."
  • Can someone else connect with you without your knowledge? "Yes," if you miss the BEEP.
  • Can someone else listen in without your (you are the owner of the phone) knowing it? "No," you have to hold a button down when talking just like a real walkie-talkie.
  • But, can an insider broadcast a meeting to an outsider without anyone else knowing it? Sure. But, this is the case with all mobile phones. This is one reason they are prohibited in certain secure facilities. (That and the cameras that come with them. See Dave Piscitello's comments here.)
So, probably this feature on mobile phones is more of an annoyance than a security risk. But, there is a similar feature in some office telephone systems: the intercom.

To my left is a "COMDIAL Impact" telephone set connected to the office phone system where I sit today as I type this. Anyone here can "Intercom" to my phone set. There is a beep and they are expected to speak, such as, "Fred? Call from your wife." Or, "Fred? Would you stop by?" Now, the important part is the notification BEEP. What if someone does this when I am out getting a cup of coffee? What if a bad guy did something to my phone so that it did not beep? Would I know someone was listening? There is a visual indication that the phone is connected to someone else's, but would I notice it? (No, I would not.) In an office environment, that would concern me more than Push to Talk. But, PTT is still more annoying.

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