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Re: Replacing PSTN with VoIP wise? Was Re: Phone networks struggle in Hurricane Katrina's wake
- From: Iljitsch van Beijnum
- Date: Wed Aug 31 17:09:03 2005
On 31-aug-2005, at 21:19, Andy Davidson wrote:
There are two types of VoIP: voice over a private, tightly
controlled IP network, and voice over the public internet. Now
obviously the latter is a risky proposition, as it imports all
the limitations of the internet into the voice service.
I'm not so sure; someone cuts an ISDN-30 into our building and the
sky falls down.
Yes, single homing sucks.
Someone cuts some fibre carrying IP and life (and communications)
carry on ..
You can get your ISDN 30 over redundant fibers too, that's not the
Perhaps you've made a fair and good comment on the marurity of most
off-the-shelf voip products or implementations. But the key, in my
mind, is that VoIP across the internet, when done well, imports all
of the opportunities of internet routing into voice service.
You say that as if it's a good thing. :-)
I think in the long run, it makes sense to have end-to-end IP calls
over the internet. However, this is not going to be as reliable as
the PSTN for many years to come, because there are is no inter-AS QoS
deployment, routing protocols take their sweet time (180 seconds BGP
timeout anyone?) and the internet is becoming fairly non-transparent
because of all the goo people keep pouring into the machinery in the
name of security and the like.
However, using the public internet as a local loop is bad. Here in
the Netherlands, the incumbent telco isn't allowed to lower its
prices, but everyone (including the incumbent telco) can sell voice
minutes to PSTN destinations over an IP "local" loop for any price
they want. So basically they're forced to kill off the local leg of
the PSTN to be able to compete on medium/long distance. This is not
good. Not so long ago, when there was a failure in the long distance
infrastructure, you could still make local calls. With the current
"intelligent" networks that's not always the case anymore, but if the
emergency number stuff is done properly, you can still call 911/112
when the long distance stuff is down. With inet local loop that will
no longer be the case in most cities.
But then, people don't really care about this, as cell is in the
exact same boat and huge numbers of people rely on just their cell
phone and no longer have a fixed line (in Europe at least).