[Asterisk-Dev] SS7 for *

[Patrick]

On Mon, 2004-10-04 at 14:25, Steve Underwood wrote:
[snip]
> > Not only that, but in the USA (at least), approval will cover a 
> > _specific_ version of the code, and will very likely not allow the 
> > code to be distributed in source form at all (because the end user 
> > could then modify it and be running a "non-approved" version).
> 
> The source code thing varies. When doing telecom approvals, I've been 
> told I could not include various information, such as source code and 
> schematics, in the documentation for the customer. Not always though. I 
> haven't been through this for a while, and things are more relaxed. 
> ISDN4Linux has been approved in the EU, and source is available in the 
> Linux kernel. They just have an arrangement whereby if you modify the 
> code it complains you are not running an approved version. I think they 
> do CRC tagging of the source, or something similar.
[snap]

A few years back I was involved in several approvals for (then) WorldCom
in Europe with Ascend ASG equipment for interconnection to European
incumbents like BT. The different versions of ISUP are a pain. That
makes it difficult from a software point of view but also in terms of
cost as you have to validate with each individual telco. And only the
soft/hardware combo that was approved is allowed for interconnection.
All seems pretty prohibitive without some serious money to get this
done. Access to a test setup with a couple of SS7 switches (and a SS7
simulator/protocol analyzer) makes things much easier. Bit rusty so with
some help from google here is some background info:

Standards to be met for e.g. BT:
* ITU-T		http://www.itu.int
* ETSI		http://www.etsi.org
* NICC PNO-ISC	http://www.nicc.org.uk

Service:
Class 4 or 5 (or both)

What to test for e.g. BT (Class 5):
* ISUP functionality
http://www.nicc.org.uk/nicc-public/Public/interconnectstandards/spec/nd1005_2000_08.pdf
* MTP levels 2 & 3
http://www.nicc.org.uk/nicc-public/Public/interconnectstandards/spec/nd1007_2001_07.pdf

Focus on:
* Signalling link management (MTP levels 2 and 3)
* Circuit management
* Call set-up, release, and failure variants
* Subscriber services (where SS7 affecting)
* Handling of invalid and unexpected message contents and sequences
* Hardware maintenance and failures
* Switch recovery actions
* Transmission alarms
* Automatic Congestion Control (ACC)

For info on SS7/C7 check out these tutorials:
* http://www.pt.com/tutorials/ss7/
* http://www.pt.com/tutorials/iptelephony/

Regards,
Patrick