Scott, Do a search on Tromboning I have no idea if asterisk is capable of doing this but I remember this was a feature introduce into Fujitsu Qsig stack in or about 94-95 which solved a heap of customer problems at the time so I remember it was a big deal.
Cheers, Dean -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Scott Stingel Sent: Wednesday, February 23, 2005 9:32 AM To: Asterisk Users Mailing List - Non-Commercial Discussion Subject: Re: [Asterisk-Users] Difference between E1 and PRI Alistair- Good writeup! Question regarding Q.SIG: Can it be used to solve the problem of signaling a remote switch to "take a call back" and extend it to another channel instead? This, as you know, is always a challenge when using IVR in a call centre environment, when one wants to extend an IVR call to a live operator without holding up channels in the IVR. Regards, Scott Stingel Emerging Voice Technology, Inc. www.evtmedia.com Alistair Cunningham wrote: > Eric, > > E1 is a physical layer protocol, like ethernet. It defines a 2Mbps > pipe, which can be used for data, or can be split into 32 64Kbps > telephone channels, or a mixture. If used for telephone channels, 30 > of these channels can carry one telephone conversation each, and 2 > carry signalling and timing information. > > T1 is similar to E1. It is used in North America. It is 1.544Mbps, and > can carry 24 telephone channels, each of which can carry a telephone > conversation (but see below). > > There are a number of protocols which can run on top of E1. Some of > these are called CAS, Channel Associated Signalling. Examples are FXS > loop start and E&M wink start. They provide information such as the > number that was called, and what state the call is in. They're limited > in what information they can carry, and are slow to set up. > > A more modern protocol which overcomes these problems is ISDN. On E1, > EuroISDN is the standard. On T1, there are different standards from > different providers. DMS100, DMS250, NI1, and NI2 are common examples. > ISDN uses one channel (called the D channel) for signalling call > information. On E1, this is one of the 2 signalling channels, leaving > 30 channels for voice (called B channels). On T1, there aren't any > spare signalling channels, so one of the voice channels is used, > leaving 23 B channels for voice. > > A PRI (Primary Rate ISDN) is simply an E1 or T1 with ISDN on top of > it. ISDN gives fast, reliable call setup and hangup detection, and > detailed information about the call. In the UK, PRI is also called > ISDN30. > > An important extension to ISDN is Q.SIG, which provides extra > signalling information that is used when connecting PBX systems. > > An alternative to PRI is BRI (Basic Rate ISDN), which is a cheaper > system for small offices. It has 2 64Kbps B channels for voice, and 1 > 16Kbps D channel for signalling. It is sold as an alternative to > analogue telephone lines. IN the UK, it is also called ISDN2e. > > I hope this answers your question! My company offers commercial > support and installation services for PRI and Asterisk if you need > help for specific scenarios. > > This email may form the basis of a future Integrics Tip. See: > > http://integrics.com/tips/ > > Alistair Cunningham, > Integrics Ltd, > Telephony, Database, Unix consulting worldwide > +44 (0)7870 699 479 > http://integrics.com/ > > > Eric Bishop wrote: > >> Hi all, >> >> I have seen the term E1 and PRI used interchangably when referring to >> a voice service with 30B channels and 1 D channel. Are they just >> different terms for the same thing or is there some technical >> difference. Even Newton's telco dictonary seemed a bit fuzzy on this >> topic. I have seen it said the PRi is a protocol that runs on top of >> E1. Is this true? >> _______________________________________________ >> Asterisk-Users mailing list >> [email protected] >> http://lists.digium.com/mailman/listinfo/asterisk-users >> To UNSUBSCRIBE or update options visit: >> http://lists.digium.com/mailman/listinfo/asterisk-users >> >> > _______________________________________________ > Asterisk-Users mailing list > [email protected] > http://lists.digium.com/mailman/listinfo/asterisk-users > To UNSUBSCRIBE or update options visit: > http://lists.digium.com/mailman/listinfo/asterisk-users > > . > _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users _______________________________________________ Asterisk-Users mailing list [email protected] http://lists.digium.com/mailman/listinfo/asterisk-users To UNSUBSCRIBE or update options visit: http://lists.digium.com/mailman/listinfo/asterisk-users
