[OpenSER-Devel] [Serdev] Possible bug in the tm module in the presence of packet loss/branches

[Jan Janak]

Dan Pascu wrote:
> It makes sense, however I still have reservations that accounting is 
> handled as one would expect in this case. While all the approach you 
> details here makes sense from a technical point of view as per RFC 
> requirements, then end user experience is different.
> 
> Consider the case where I call a number that has a high setup fee, say 5 
> euros only to connect even if the call duration is 0. While I wait for 
> this call to setup, I receive no provisional reply, so my phone is not 
> ringing. Then I change my mind and hang-up the phone. My end user 
> expectation is that the call was not setup and I have nothing to pay for. 
> But in reality, if there is network packet loss and a scenario like the 
> one described before happens, the call will actually be setup and show up 
> like a 0 second call with a 5 euro price, not as a canceled call.

  The same can happen even if you receive a 180 and hangup while the
  phone is ringing. I, as a user, would expect not to be charged, but if
  a 200 OK made it to the server then I would probably see it on my
  bill.

  So the race condition is there in anyway. If you want to be just to
  your users then you probably should charge the high setup fee only if
  the call took at least a few seconds.

  Seeing a high setup fee on your bill and a call duration of 0 looks
  strange in any case, no matter what was going on in signalling.

     Jan.