[asterisk-ss7] Nx64k and ISUP

Gustavo Mársico gustavomarsico at gmail.com
Fri Dec 9 18:09:05 CST 2011

Hi Michael

From the user perspective, they selected the number of channels to be used, and the speed of those channels. Off course for ITU-T world you cannot select any value different than 64kb/s because the protocol itself don't allow it. If the user selected 2 channels you can use as N calls of 64kb/s (independent) or bonding mode. In bonding, you selected how many channels you like to use, the A side equipment made one call marked as Nx64 (used internally in the switch to reserve time slots). As soon as the remote equipment answers the call and accept the handshaking the A side equipment made the rest of the calls, all at the same time. There was no way to control the path of those calls, and was funny to see videoconference calls using 20x64k going back and forth caused by the delay on one of the paths (something like Max Headroom).
When I went to 60 Hudson (12 years ago) to see the equipments, the guys from AT&T explained to me that the calls using 64kb/s used a entirely different network using ANSI ISUP, with a special Transmission Medium Requirement. They used a 5ESS with 15 version (if I'm not mistaken) with ITU-T and ANSI software loaded as international gateway (Axe10 can do the same, and it was used for other carriers in the same building). That switch routed the calls according the TMR and the Forward Call Indicators. I'm sure that I've some traces backed up, if I find it I'll sent it to you for historical purposes.
They also told me how the last switch managed the 64kb/s channel, but I don't remember how (in fact I didn't paid the proper attention because I was a TDM transit guy).

Anyway, if I get more information I'll let you know.



On Dec 9, 2011, at 11:59 AM, Michael Mueller wrote:

> moved this to another topic...
> this is interesting; i've never known anyone who has seen this
> actually working; can you describe how it was used
> how did the end user use it? what was the bandwidth for? who was the
> end user - a human or a machine?
> 2011/12/9 Gustavo Mársico <gustavomarsico at gmail.com>:
>> Just as a remark, there were a lot of BRI lines in USA using 64k. We ran
>> ISDN videoconference stations in AT&T CALA to US in early 2000's (using AT&T
>> and Sprint networks). They'd some DS1 with 64k channels to support
>> international Nx64k calls with ANSI ISUP, but I'm not sure if that network
>> remains active.
>> Anyway, that was just a comment about this interesting subject.
>> Gustavo
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