Talk:Signaling System No. 5

I believe that the line signalling element of #5 is compelled, whereas the register signalling element is pulsed (i.e. non-compelled). If anyone can authoritatively confirm this, then I suggest that they add this fact to the article. JanCeuleers 15:49, 31 January 2007 (UTC)

Misunderstood technology
The title of this article does not exist, at least in that form. Before digitalisation there were three classes of signalling. All began with Signalling System in the title. We had SSAC (Signalling System Alternating Current) where there were at least fifteen types, SSDC (Signalling System Direct Current) with at least ten types and SSMF (Signalling System Multi-Frequency) with six types (I think). We hardly ever used the full title, but shortened it to AC1, DC5 or MF4. So the correct name for this thread should be MF5, which I believe was used in the BPO transit trunk system. This system used multiple signalling classes. AC11 which just seized and released the circuit and MF5 which conveyed the routing information. MF5 used request to send, clear to send and retransmit tones as well as tones for the digits.

Steve G1cbk (talk) 06:25, 13 June 2024 (UTC)


 * Different side of the pond, different terms. The Atlantic Code (slang) or CCITT5 (official ITU designation) was adapted mainly from the MF code of the Bell System, with modifications including double-stage pulsing so the intermediate Toll Points wouldn't need to handle the extra digits. In the early 1970s, as one of Ma Bell's happy little dingalings I installed IDDD (US designation) in Manhattan local exchanges, and familiarity eased my job. However, I don't think we should prefer either American or British designations though they are well known to us ancient speakers of English, nor should we prefer whatever the French called it. Jim.henderson (talk) 01:50, 16 June 2024 (UTC)