Hi, I have a question. Where are transmitted the multifrequency signals? (Time slot 16 uses four status bits for signaling purposes - Supervisory Signals). Interregister Signalling - I don't now. Time slot 16 in frame 0 is used for Super Frame alignment. Maybe in the next frames (1 through 15)? Thanks for help
R2 (MF) is inband (audible) signalling over an individual R2 trunk or a T1 span of 24 (usually E&M wink start) trunks. Their most common use in the USA today is for E911 services.
Regardless of whether MFC/R2 is being carried on a digital (e.g. E-1) or an analog trunk, the address signals are in-band, and thus are carried in the voice path. For E-1, this means that they are in-band tones carried on the specific channel (timeslot 1-15 or 16-31). The line signaling is carried in the A-D bits of timeslot 16 on an E-1, as they are out of band signals. On an analog trunk, this would be transmitted via the E&M leads.
address signaling = register signaling = in-band tones line signaling = supervisory signaling = out of band signals (bits, or polarities).
Since this would be a 4-wire circuit, the forward signals would travel in the forward part of the transmission path, and the backward signals would travel in the reverse part of the transmission path.
Welch's book "Signalling in Telecommunication Networks" (ISBN: 0 906048 46 X) is an excellent reference for this.
Regards,
Bob
I think you are confusing R1 and R2. R1 (Regional signaling system 1) is the North American variant of multi-frequency signaling. Formerly used in the long distance network, it is still quit prevalent in the US network. However, its primary function is to provide a simple signaling interface to connect adjunct boxes to the network. Examples of such adjuncts would be 911 systems, voice mail systems, prepaid card systems, billing systems, etc. It is much cheaper and simpler to interface a new box you are building to the network via R1 than SS7.
R2 is what's used everywhere else. It's commonly called MFC, or Multi Frequency Compelled. This is a system with forward and backward address signals, making it very flexible for a variety of applications (e.g. local, toll, international). Compelled means that the forward direction doesn't remove its forward signal until it hears an answering backwards signal. While quite flexible, this compelled nature tends to make it slow. There are semi-compelled variants that attempt to shorten the time it takes to complete a signaling sequence. R2 is still in use around the world, both for interoffice trunks as well as CO-PBX interface.
Bob
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