On Fri, 2008-08-01 at 13:42 -0400, Steve Totaro wrote: > On Fri, Aug 1, 2008 at 1:30 PM, emist <[EMAIL PROTECTED]> wrote: > > Hey Trixter, > > > > Can you explain a bit more about the "early media" adverts and why there > > aren't any per minute charges? > > > > Thanks, > > > > Igor H. > > > > Try the first or second hits on Google. > http://www.jdrosen.net/sip_early.html > http://www.faqs.org/rfcs/rfc3960.html > > You can send audio before answering, thus not be billed since the call > was never answered. >
correct. This enables you to open a media path, send audio (sometimes receive it) and all that. Its how "custom ring tones" are done, and similar things. I have noticed a bit of an issue relating to international calls at least. I set up a geographic number I had in no media mode, meteor (Irish mobile company) routed a call there, and I was able to hear perfectly fine, one way audio, no dtmf, and it cut me off at exactly 60 seconds. This is also how some error messages are sent (not all). Really you can send almost anything you wanted in this window, even conveying information to the remote endpoint automagically (example would be a IP route around to avoid pstn charges - a protocol exists that I wrote a couple years ago but never did anything further with it, I heard that some others were trying to do a modified version of what I did about a year ago). I should still have the pdf that I did of this protocol (based on DTMF to make it more portable) if not I know that the people who are doing a modified version have it because I gave it to them. The reason you can open the audio path is because on the pstn the entire circuit is allocated before the remote phone rings. Since the circuit is allocated, it is not that difficult to use it, answering supervision (the signal that says the phone is now answered) is separate from engaging the circuit. -- Trixter http://www.0xdecafbad.com Bret McDanel Belfast +44 28 9099 6461 US +1 516 687 5200 http://www.trxtel.com the phone company that pays you! _______________________________________________ --Bandwidth and Colocation Provided by http://www.api-digital.com-- AstriCon 2008 - September 22 - 25 Phoenix, Arizona Register Now: http://www.astricon.net asterisk-biz mailing list To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-biz
