Talk:Signaling System 7

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[edit] Updating Ss7stack

I think the SS7 stack could do with being updated to show TUP as one of the L4 protocols and then cross-reference this to the TUP article. I guess this is controlled by the inclusion of the reference to "SS7stack" within two pairs of curly brackets. I can't work out how to edit this. Any pointers as to how I go about editing this would be appreciated. --AndyAicken 13:09, 7 November 2006 (UTC)


The "Stack" is also very misleading. For instance ISUP is not dependant on SCCP as a transport layer, only MTP levels 2 & 3 are used. Same would be true of TUP. The stack is also inaccurate in one important respect. There is no such thing as MTP Level 1. Level 1 is the physical layer, it is not part of the MTP as no "messages" are transported. 217.36.0.13 14:40, 26 March 2007 (UTC)

Quote from Q.701:
"The functions of each level of the MTP are performed by means of the level protocol between two systems which provides a “level service” to the upper levels (i.e. level 1 Signalling Data Link, level 2 Signalling Link and level 3 Signalling network) as described in Recommendations Q.702, Q.703 and Q.704 respectively."
MTP level 1 is the Signalling Data Link. 195.10.3.194 16:59, 26 March 2007 (UTC)
OK, the {{SSstack}} template is now in that section (although it's also, I just noticed after editing the section on its own, at the top of the article... damn), and I've reworded the whole MTP1-3, SCCP, TCAP, TUP/ISUP part. I can't, off hand, think of any users of SCCP other than TCAP, although I'm not sure if the BSSAP is a TCAP user on top of SCCP, or uses SCCP in connection mode directly. Also, I've sort of hinted at the fact the TCAP article is misnamed - TCAP doesn't stand for Transaction Capabilities Application Part - never has, never will. It's Transaction Capabilities, as clearly evidenced by the titles of the Q.77x series of standards. 86.144.170.33 21:33, 26 March 2007 (UTC)

Regarding the previous comment that ISUP does not use SCCP as a transport- the question is then- why SCCP has a subsystem called ISUP? I have seen meny tutorials saying that ISUP can be a SCCP user... However I have not ever seen such things in real life, if anybody can explain this part it would e good.

-Dmitry

Hi Dmitry. I can't think, off the top of my head, of any technical reason why ISUP couldn't sit on top of SCCP. It's just that... why would you want to use it in that manner? SCCP doesn't really buy you anything for ISUP routing, and you lose a (small) amount of MSU payload size for the SCCP labels, routes and headers. I'm not guaranteeing this answer, but it seems reasonable to me. Carre (talk) 12:44, 9 January 2008 (UTC)

[edit] Re: SS7 vs. C7

It is my understanding that SS7 relates to the ANSI standard while C7 relates to the ITU standard. Although with many things in common they are diferent in for example things as the addressing space.

[edit] Re: SS7 vs. C7

I believe SS7 and C7 to be synonyms. Often you will also find CCS7 for "Common Channel Signaling (System) 7". But yes, there are certain subtle differences wrt. e.g. lenghts of certain protocol fields such as CIC.

[edit] Re: SS7 vs. C7

Yes, SS7, C7 in common nomanclature references the signaling network.

There is no mention of the links or entities that create the SS7 network, IE: SSP, STP, SCP

Now with respect to the links themselves: 'A' Links = Access Links 'B' Links = Bridge Links 'C' Links = Cross Links 'D' Links = Diagonal Links 'E' Links = Extended Links 'F' Links = Fully associated Links

Now; there is also the database functionality that gets associated to the SCP. Also it should be noted that SS7 is a seperate network; and functions as an over lay to the PSTN. Ahh; this article will grow with time. Regards, Pete

[edit] C7 vs SS7

I've always thought of C7 as denoting the European standard, with the C standing for CCITT; similarly, I've seen J7 (Japanese variant), and A7 (ANSI variant).

Also, while I'm here, I'd say CAMEL should have a link off the main page.

[edit] Adding a link to the 'Products' section

Looking at the links on the 'Products' section I think this link to Aculab's SS7 offering would not be out of place: http://www.aculab.com/products/ss7.htm IANCEE 11:01, 2 October 2006 (UTC)

I've also added a link to Squire Technologies SS7 products: http://www.squire-technologies.co.uk/products/index.html. --AndyAicken 13:09, 7 November 2006 (UTC)

The number of links in the "Products" section appears to be getting excessive per WP:NOT#REPOSITORY and WP:NOT#DIRECTORY. -- Rob.au 09:21, 7 March 2007 (UTC)

[edit] Historical Inaccuracies

SS7 is relatively new nomenclature for what has historically always been known as C7, first under the CCITT then ITU/ETSI banners. When I first started working in the Telecommunications industry back in 1988 there was no mention of SS7 anywhere in any literature. Even when communicating with engineers in the USA the terminology used was always C7. There was no such signalling system as SS6, it has always been called C6 and it's not appropriate to retrospectively rename it to "fit in" with the new naming convention of SS7. The C naming convention has nothing to do with the ANSI or CCITT/ITU/ETSI variations of the signalling system, it relates to the fact that it is a Common Channel Signalling (CCS) system as opposed to a Channel Associated Signalling (CAS) system.

The ITU calls it SS#6 (see the ITU-T standards page). So, appropriate I guess it is. 195.10.3.194 17:10, 26 March 2007 (UTC)

[edit] Remove products section?

I'm proposing the total removal of the products section, and probably the services section too. These sections and their contents add nothing to the article, the lists are an arbitrary selection from the look of them (no Lucent, Nokia, Ericsson, Siemens, Alcatel etc... even if those companies all seem to be merging together at a rapid rate of knots!). It seems like pointless spamming and commercial content that has no place on Wikipedia. Where a commercial site has something that actually adds to the article, such as a white paper or tutorial, then it could be linked as a reference to text in the main article, but as it is it's just a directory, and an incomplete one at that.

Objections from anyone (apart from the people who have added their own companies details, of course, since objections from such quarters are possibly biassed). 195.10.3.194 16:32, 19 April 2007 (UTC)

Normally I would recommend deleting both the Products and the Services sections but User:Bradams recently did some general link clean up. I suggest we give Bradams' efforts a chance. If Bradams isn't monitoring this thread, suggests deletion, or if the spamming becomes a big problem then by all means remove those spam magnet sections. (Requestion 16:53, 19 April 2007 (UTC))
I saw the link clean ups in the history (sorry, the above IP address addition was me, from work). I think one of my major concerns is that several of the links in those sections aren't particularly notable in the field, whereas there are gaping omissions, as indicated in my IP addy post. Looking at the rest of the article, it seems to have a predominantly US authorship (note, not -centric; the content is pretty good thus far), hence perhaps the lack of the European big vendors like Nokia et al, but no Lucent? Cisco, Ulticom & Nortel are all big players in the signalling/network world, so perhaps deserve a place. Aculab is based, or at least has a presence, just up the road from where I live, so I know of them but am not sure of their prevalence in the field; as far as I'm aware, they make line cards for signalling, as well as DSPs and the like. The rest are unknown to me, at least, and I've been in the telco industry for about 12 years. If the sections were to remain, I'd personally prefer it if the non-notable links were ditched, and the big players put in instead (although I'd definitely prefer the lot to go).
In any case, I'll follow your advice and see what Bradams comes up with, if anything. Carre 19:32, 19 April 2007 (UTC)

[edit] Plagiarism?

Certain sections of this article have been directly pulled from other copyrighted sites. In particular the "Functionality" section is pulled directly from IEC WebPro Forums. Would suggest leveraging this tutorial as well as another found at this site in order to cleanup the article and provide necessary citations.

I'm new to this section, so please feel free to give me feedback on what I've proposed. I don't want to step on anyone's toes, but would be happy to help with the above. Witt04gti 20:26, 16 May 2007 (UTC)

I just edited your comments on this talk page to go in the order entered - makes it easier to understand. Hope you don't mind.
Anyway, to your point - if this is, indeed, plagiarism, it should be removed/edited/fixed as soon as possible! (I haven't checked, and didn't write that bit of the article.) I have been going through numerous telecoms protocol related articles recently, trying to improve them, but there are a huge number of, frankly, pretty poor examples on the wiki at the moment, and it's a struggle to even know where to start fixing them! Any help is much appreciated. In cases of plagiarism, like this, a good way to fix it would be to paraphrase available sources, and cite the sources. Avoid just linking to external sites with no explanation, as such links are likely to be removed as link spam. Carre 21:06, 22 May 2007 (UTC)

[edit] Functionality (Automatic Redial Example)

Someone made an edit on 11 May 2007 that changed the *66 reference to *69. Quick poll of the major telecom websites shows that *66 was indeed correct. I'm reverting it back. Witt04gti 00:02, 19 May 2007 (UTC)

[edit] Basic questions

This article may be too technical for a general audience.
Please help improve this article by providing more context and better explanations of technical details to make it more accessible, without removing technical details.

This article leaves some basic questions in the mind of the lay reader.

  • If the protocol no longer uses audio tones to transmit signals, is it now all digital ASCII text like TCP? Can we see an example?
  • Is this something that the phone in my hand has to speak, or is it only something that the central office computers speak to one another?
  • If all central office computers in the world don't speak this protocol, does that split the PSTN into multiple parts that cannot mutually communicate or require manual intervention?
  • What part of this applies to cell phones vs. landlines?

-- Beland 19:24, 25 September 2007 (UTC)

Thanks; we do need outsiders to keep us from just talking among ourselves. Mostly these questions belong in the linked PSTN article, which also doesn't cover such things very well. No, it's not ASCII; it's ISUP and that article is also a lot clearer to insiders than outsiders. No, the local loop uses older pulse dial and DTMF signaling, and SS7 is only among exchanges. Where some exchanges don't speak the language, a tandem exchange will translate as well as tandem the call through. None of it is cellphone; their exchanges translate to/from SSt but again we need to get all this into the various articles, since the encyclopedia isn't intended for us who already know. Jim.henderson 19:50, 25 September 2007 (UTC)
Beland often puts very useful and relevant questions in SS7 related articles (I've found them useful on some I've been involved with, anyway), and reading the article and Jim's responses here, there's definitely a need to work on these!
  • The protocol(s) don't use ASCII - they all pretty much define, within the relevant standard, how messages are encoded. TCAP users typically use ASN.1 (Abstract Syntax Notation) to define the coding. MTP, SCCP and the various call-related protocols use different encodings. ISUP is only one of the various components of SS7 - there are other call-related user parts (Telephony User Parts and National User Parts (TUP & NUP)) out there, although ISUP is gradually achieving dominance on the call setup side.
  • As Jim says, the handset doesn't speak SS7, but the local loop doesn't necessarily just use pulse or DTMF... I vaguely recall doing some DPNSS or DASS2 (can't remember which) work for C&W in the UK a few years back, for handling local loop signalling.
  • Jim's answer for the tandem exchange is spot on, to the best of my knowledge. There are still, however, occasional interworking problems, particularly interworking between GSM and ANSI networks.
  • In the cellular world, GSM networks are entirely SS7 based, from the Central Office all the way out to the Radio Access Network (RAN) - the Air Interface (not an area I've ever worked on) doesn't come under the umbrella of SS7. Even UMTS networks still use SS7. I know next to nothing about N. American mobile networks, but I do know there are ANSI equivalents of TCAP and MAP (AS-41, off the top of my head).
I'm not entirely sure how to address this particular article - perhaps go all the way back to first principles, and use the Q.7xx specifications to properly define at least MTP 2 & 3 (that would answer the {{huh}} against the linkset part in the article). These days, unfortunately, I've pretty much stopped editing signalling related articles. Carre 16:39, 28 September 2007 (UTC)
Hah! I knew I was ignorant on GSM; just didn't appreciate how ignorant. Anyway a few minutes ago I added a first draft of a history subsection (forgetting to log in) in PSTN which I hope can help some readers. This SS7 article I figure also should be improved for civilians, but really it is a specialized concept and more needs good connections to other articles handling elementary points and background, than an introductory section. That is, unless someone proves me wrong by writing a good introduction here. Certainly there should be better presentation of the place of ISUP, TUP, NUP, whatever, within SS7, and SS7 within GSM. Anyway, the points that very much require clarification are not the deep ones about specifications and such, which only insiders will understand anyway, but shallow questions which any intelligent and curious outsider will ask, which insiders take for granted. Jim.henderson 02:25, 29 September 2007 (UTC)