[EMAIL PROTECTED] wrote: > http://www.voip-info.org/tiki-index.php?page=Bandwidth%20consumption > > A T1 set up for voice uses G711 at 64Kbps which at 1.544Mbps > equals 24 channels. This is also known as a PRI.
No, that is incorrect. PRI is a type of ISDN service that is typically carried across one (or more) T1s. The PRI-ISDN service uses one of the 24 channels in the T1 as a signalling channel (or D-channel), the other 23 channels become the bearer-channels (or B-channels). PRI is sometimes referred to as 23B+D, but in reality can be built far more creatively than that. Many large PBXs will have a single PRI circuit that is delivered on two T1s, with a primary and backup D-channel in each T1 (46B+2D). If you wanted, you could save the backup D-channel and have a 47B+D (bad idea, but technically possible). It is even possible to have a D-channel running across a serial link, completely out of the T1 altogether; although I haven't seen one of these in a long time . . . To summarize: A T1 is a *circuit*, that can be used to carry all kinds of different services. PRI is one kind of *service* that is commonly carried over a T1. Cheers, Jim. > > -Matthew > > ----- Original Message ----- > From: "Ed Greenberg" <[EMAIL PROTECTED]> > To: "Asterisk Users Mailing List - Non-Commercial Discussion" > <[EMAIL PROTECTED]> > Sent: Thursday, December 16, 2004 11:45 AM > Subject: [Asterisk-Users] Calculating required bandwidth > > >> I was posed this question: >> >> A T1 set up for voice carries 24 conversations on a circuit that is >> 1.544 megabits/second. Right? >> >> Well, if you set that T1 up to carry data and run a link between two >> IP networks over it, how many SIP conversations could it be expected >> to > carry? >> How about IAX? >> >> How would one extend this calculation to varying bandwidth circuits >> and various VOIP protocols (MGCP, SCCP and H323 come to mind)? >> >> Rather than asking for a full education here, can somebody point me >> at a suitable practical reference? Of course, if somebody wants to >> actually > post >> the answer that'd be fine too :) >> >> THanks, >> </edg> >> >> >> _______________________________________________ >> 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
