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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 problem.

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).




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