>Even if the terminating switch does not speak SS7, the originating switch=
 knows
>whether or not the call has connected and provides a connect indication to=
 the
>ISDN terminal.  I'm not sure of the mechanisms that allow the originating=
 switch
>to know that the call has been connected, but it has to know so that it=
 can
>notify the terminal to go to the call connected state.

        Audio tones! In Brazil, is used around 12 KHz (!) to signal a "call start"=
 and another to burn a fuse of the inductive card, used to store payphone=
 credits.

>As an interesting aside, a few years back, our local exchange changed the=
 way
>they handled calls to the time service.  It used to be that the calls=
 would
>connect then the time lady would announce the time of day.  Now the time=
 is an
>intercept message, and the connect never happens.  I was told that was=
 done to
>make things easier for their billing department, because calls to the time=
 are
>free, but local ISDN voice calls are tariffed.  The change made things=
 easier
>for their billing system, but blew a hole in some of my test procedures.

        wow...


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Alexandre Souza
taito@terra.com.br
http://planeta.terra.com.br/lazer/pinball/

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