Phasing out of telco TDM Backbones (was: Phasing out of copper)

Måns Nilsson mansaxel at
Sun Nov 30 09:30:57 UTC 2014

Subject: Phasing out of telco TDM Backbones (was: Phasing out of copper) Date: Sun, Nov 30, 2014 at 12:09:40AM -0500 Quoting Jay Ashworth (jra at
> ----- Original Message -----
> > From: "Måns Nilsson" <mansaxel at>
> > Maintaining copper plant is expensive. It will be retired as soon as
> > buy-in on FTTH is high enough. Telia Sonera is doing it in Sweden,
> > so the trend is global. (OTOH, in Sweden, young people moving out from
> > their parents, if they can find somewhere to rent, usually only get a
> > fixed connection for Internet access. Telephony is all mobile.)
> Absolutely: maintaining analog copper last-mile is expensive.
> But let us not conflate being ok with telcos replacing analog copper last-mile
> with being ok with telcos replacing PCM with VoIP, especially in trunking
> applications, and *especially* using non-dedicated backbones, as these are the
> directions the RBOCs appear to be going in, and those are much less acceptable
> ideas than the former.

Sadly enough, those man-centuries need to be reread in the light of the
fact that today, you can not buy most of those connections anymore. Voice
circuits are almost entirely trunked on IP; and the telcos fight to
decommission the carrier formats.

From 2014-12-31, you can't keep your 128kbit ISDN anymore in Sweden. This
is a big issue for me, since I work with radio broadcasting. There,
128kbit ISDN is a very common way to do remote broadcasting from
sports or similar events. We've been frantically buying and building
a new network to replace these circuits, and have built a quite nice
system on top of IP. The old ISDN codec phones (essentially small pro
mixer + A/D converter + MPEG codec + ISDN terminal) are being replaced
by similar-looking specialised SIP phones sporting much higher sound
quality. If the network permits (and, on those sites where we expect
to do live music, it does permit so) we can do 48KHz 24bit uncompressed
stereo  -- which is around 2,6 Mbit without protection by FEC.

Since the voice circuit is mostly being replaced by the Skype/FaceTime
call, this is not only a special observation; it is, I believe, a general

Our challenge thus lies not in preserving circuit-switching,
but instead in building an open, standards-based voice infrastructure
on top of IP. Viewed in that light, Skype and FaceTime are failures. I'm
not certain their owners see it that way.

/Måns, who *really* would like to have STM-64 frames instead of TenGig
       Ethernet for his long lines. Switched Ethernet is herded chaos. 
Måns Nilsson     primary/secondary/besserwisser/machina
MN-1334-RIPE                             +46 705 989668
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