Wasn't the 56/64k thing a result of CAS (bit robbed) signalling which was a fudge AT&T did to transport signalling information in-band on T1s by stealing the low order bit for OOB signalling (it wasnt actually every low order bit, but meant you had to throw away every low order bit as CPE didn't know which ones were "corrupted" by the carrier).
Proper ISDN was always 64kbit/s clear path with separate D channels carried OOB end to end, away from the B channel data.

On Mon, 27 Jan 2020 at 11:57, Mark Andrews <marka@isc.org> wrote:
The hardware support was 2B+D but you could definitely just use a single B.   56k vs 64k depended on where you where is the world and which style of ISDN the telco offered.


--
Mark Andrews

> On 27 Jan 2020, at 22:32, Bryan Holloway <bryan@shout.net> wrote:
>
> I didn't think one could get a single 'B' channel over ISDN ... but I could be mistaken.
>
> In my early ISP days, ISDN was 2 x 64k (full-rate) 'B' channels and a 16k 'D' channel for signaling.
>
>
>> On 1/26/20 5:58 AM, Joly MacFie wrote:
>> IIRC that 64k was in fact 56k with 8k for overhead.
>> I had one, and it would kick in a second channel if you pushed it, for a whopping 112k. Metered, came out to about $500/mo.
>> Joly
>> On Fri, Jan 24, 2020 at 6:26 PM Ben Cannon <ben@6by7.net <mailto:ben@6by7.net>> wrote:
>>    I started what became 6x7 with a 64k ISDN line.   And 9600 baud modems…
>>    in ’93 or so.  (I was a child, in Jr High…)
>>    -Ben.
>>    -Ben Cannon
>>    CEO 6x7 Networks & 6x7 Telecom, LLC
>>    ben@6by7.net <mailto:ben@6by7.net>
>>>    On Jan 24, 2020, at 3:21 PM, bzs@theworld.com
>>>    <mailto:bzs@theworld.com> wrote:
>>>
>>>
>>>    On January 24, 2020 at 08:55 aaron1@gvtc.com
>>>    <mailto:aaron1@gvtc.com> (Aaron Gould) wrote:
>>>>    Thanks Jared, When I reminisce with my boss he reminds me that
>>>>    this telco/ISP here initially started with a 56kbps internet
>>>>    uplink , lol
>>>
>>>    Point of History:
>>>
>>>    When we, The World, first began allowing the general public onto the
>>>    internet in October 1989 we actually had a (mildly shared*) T1
>>>    (1.544mbps) UUNET link. So not so bad for the time. Dial-up customers
>>>    shared a handful of 2400bps modems, we still have them.
>>>
>>>    * It was also fanned out of our office to a handful of Boston-area
>>>    customers who had 56kbps or 9600bps leased lines, not many.
>>>
>>>    --            -Barry Shein
>>>
>>>    Software Tool & Die    | bzs@TheWorld.com
>>>    <mailto:bzs@theworld.com>             | http://www.TheWorld.com
>>>    <http://www.theworld.com>
>>>    Purveyors to the Trade | Voice: +1 617-STD-WRLD       | 800-THE-WRLD
>>>    The World: Since 1989  | A Public Information Utility | *oo*
>> --
>> ---------------------------------------------------------------
>> Joly MacFie 218 565 9365 Skype:punkcast
>> --------------------------------------------------------------
>> -



--
--
Rob Pickering, rob@pickering.org