>From what I've heard and learned, SS7 appears to be a meta meta signalling protocol.
First we had analog lines. Then ATT started grouping 24 analog lines to form a T1. Inband signalling was used in each channel. Time studies indicate that these channels can be more effectively used if the signalling (ringing, busy, etc) is removed out of each channel and put into a common data channel, or D Channel as they call it in ISDN parlance. So for a North American PRI line, a T1 with 24 channels is sectioned off into a 1 D channel, which is used for signalling, and 23 B channels (bearer channels) which are used strictly for voice traffic. So ISDN/PRI lines use meta signalling to control the voice channels. SS7 is strictly a signalling and control protocol. It carries no voice traffic, but controls how voice is routed between locations. For instance, some one picks up the telephone and dials a number across the country. The local telco switch signals the telco switch at the other end to ring the destination phone. This signalling is handled by SS7. If the destination party picks up, it is at that moment when the the source telco and the destination telco open up a voice circuit and connect the two parties. If the destination party does not pick up, and the source party hangs up, no voice channels have been opened up, and the telco enjoys a cost saving by not having to dedicate a resource to the conversation, such as like back in the good old days of RBS (Robbed Bit Signalling) T1's. SS7 also handles the CLASS series of value-add signalling services. SS7 is therefore useful for handling the signalling on large channel volumes (loosing a B channel to a D channel in a PRI for every 24 channels is expensive overhead), and is good for geographically distributed dialling plans. So, to wrap up, SS7 is a meta meta signalling protocol. It controls the signals going down a PRI which signals the PBX on what it needs to do with the call. If any others on this list can contribute their thoughts and experiences, it would be greatly appreciated. Regards, Ray Burkholder http://www.oneunified.net 704.576.5101 > -----Original Message----- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Brad Waite > Sent: October 27, 2003 15:22 > To: [EMAIL PROTECTED] > Subject: Re: [Asterisk-Users] SS7 signaling/Softswitch > > > CW_ASN - Gus wrote: > > > Anyway, in certanly implemetations you don't need CCS7 to > connect to CO. You > > always can connect with PRI... same speed and same > functionalities to user > > side. In fact, CCS7 is the support for ISDN-PRI avanced > features. If you > > could connect with Lucent 5ESS you can have a PRI treated > as route... > > Gus, > > I'm not following you here when you say, "...you can have a > PRI treated as > route..." Can you clarify? > > I'm trying to determine what AIN features may be available on > a PRI D channel. > I know the D channel is a near extension to SS7, but I don't > know what subset of > queries/commands are available between the two. > > Brad Waite > W Cubed > > _______________________________________________ > Asterisk-Users mailing list > [EMAIL PROTECTED] > http://lists.digium.com/mailman/listinfo/asterisk-users > > -- > Scanned for viruses and dangerous content at > http://www.oneunified.net and is believed to be clean. > -- Scanned for viruses and dangerous content at http://www.oneunified.net and is believed to be clean. _______________________________________________ Asterisk-Users mailing list [EMAIL PROTECTED] http://lists.digium.com/mailman/listinfo/asterisk-users