El Jueves, 11 de Junio de 2009, Paul Kyzivat escribió: > In one case I have a single phone with one phone number. Typically if a > 2nd call comes in while phone is in use it is signaled to the callee in > the media stream rather than through "ring". To switch between calls you > typically use "flash". This is case where typically the caller might get > a "call waiting" signal. (Because this case is considered a "call > waiting" feature.) > > A 2nd case is where I have a "desk phone" with multiple "line" buttons > on it. Those "lines" may be associated with distinct phone numbers. By > pushing the line buttons you can connect the microphone and speaker to > one or the other of the "lines". While a call is in place on one line, a > call may come in on the other "line". Typically the signaling in this > case would still be a ring, or maybe a flashing of the light on the line > button, or both. To switch and answer the 2nd call you might have to > first push HOLD and then press the button for the other line. In this > case, AFAIK, the caller is *not* likely to get a "call waiting" signal.
For the caller signalling perspective both mean the same: the callee is on a call but has notification of this new call. > The above are "traditional" renderings of a couple of different > services. But fundamentally they are almost the same. In particular, the > increased effort and delay to answer the 2nd call is pretty much the > same in both cases. So if it makes sense to alert the caller to this in > one case, it ought to make sense to do so in the other case too. I agree, it's exactly the same (jsut different technology but some concept). > OTOH, I am not convinced that it makes sense in either case. Being "on > the phone" at least means you are *near* the phone. So the time to > answer may actually be less, on average, than when you are not on the > phone. So what is the point in signaling anything special? If I call somebody (my boss) and receive "Call-Waiting in remote side" indication, I could hang-up inmediatelly and call later (this is really useful in case my call is not urgent at all and I don't want to disturb my boss who could be on an important call). > If anything, it would be better if the callee could cause a signal to be > returned to the caller that affirmatively indicated "I acknowledge your > call, but will need extra time before I can answer it". The Call-Waiting indication in the response could be generated in varios ways by the callee: - Automatically when an active line already exists. - Never. - Manually by pressing a button (notify call-waiting to caller). These options could be configurable in the phone. So, if we consider 182 valid for this purpose (and I think we all agree) then this feature would require: - UAC implementation (display "The remote is actually on a call" upon receipt of 182). - UAS implemetation (with the options I mention above). Do yo agree? Thanks a lot for your comments. -- Iñaki Baz Castillo <i...@aliax.net> _______________________________________________ Sip-implementors mailing list Sip-implementors@lists.cs.columbia.edu https://lists.cs.columbia.edu/cucslists/listinfo/sip-implementors
