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isn-discuss - Re: [isn-discuss] ISN dialing, numeric alternative to * key ?

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Re: [isn-discuss] ISN dialing, numeric alternative to * key ?

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  • From: "Jonathan Cohen" <>
  • To: <>
  • Subject: Re: [isn-discuss] ISN dialing, numeric alternative to * key ?
  • Date: Thu, 30 Mar 2006 10:44:23 +0100
  • Organization: None

string, and inverting the ITAD/subscriber order. However, I argued that the ISN numbering scheme is going to be enough of a trial to get people to remember, and anything that requires thought or examination of the numbering pattern in order to dial will present insurmountable psychological barriers to adoption. Think of explaining this to

I agree, however the problem is with variable length ITAD and user numbers, without the (*) separator there's no easy way to break the two apart. Shouldn't this be the kind of thing the trial resolves?

With those factors, rotary phones were consciously considered and after quite a bit of painful thought were recognized as incompatible

We're not talking dial phones here. Even less that 10 years ago here in the UK we had BT exchanges that only accepted LD (loop disconnect) signalling. We're talking about (sometimes less than 10 years old) push button telephones and systems that only use LD signalling (no * or # keys). They're still regularly found here in the UK (though many can be easily switched to DTMF) and are very common across Africa and Asia. I can't find any statistics but I know from experience that in many parts of Africa LD only phones must be greater than 50% of the installed base (often being second-hand phones from the UK). In fact our biggest challenge has been adding old PABX CCUs between systems to convert from LD to DTMF to link in to a VoIP ATA etc.

confusing and will be less adopted which the other 95% of the world's population can use with a lower barrier of adoption.

The trouble is that we're excluding people based on their technical and financial status. Lets face it, here in the western world we don't really need VoIP to reduce the cost for voice calls, as (mobiles excluded) once you have a PSTN connection (usually needed for internet access anyway) you can call pretty much anywhere in Europe/America/Australia for 1p (< US$ 0.02) per min. I see the technology as an enabler. We can add new services such as video etc where these would have been cost prohibitive before and in the developing world provide low cost service where previously the only method of communication was expensive and unreliable mobile or satellite phones.

I've spent my life trying to create communications systems that are simple, reliable and low cost so I really understand what you're saying. However, surely the whole point of the ISN trial is that it's a stepping technology from what we have now to what we would like in the future? Not a means to exclude the poor or force a technology upgrade? ;-)

As a last note: even in Africa, the use of pulse phones is rapidly dwindling, though of course at a much slower pace than had been experienced in more affluent portions of the world as far as the landline base is concerned. The flood of surplus equipment coming out of Western nations is causing quite a bit of updating, and there are even complete skips of digital phone systems directly to IP-based transport as cell phones become more dispersed.

See above, LD signalling is still common. You're right about the flood of surplus equipment, we're using such systems ourselves, however the life of a phone system or PBX can be long (typically 10-20 years) and even if replacement equipment is free, finding people with the experience to install it (or even re-program old systems to use DTMF if possible) can be very difficult and expensive in many locations. It's much easier (at least initially) to provide a gateway that converts the existing LD signalling to MF and feed that to an ATA.

Much of the African population (if they have phone access at all) currently only have access to mobile phones and these (even in capital cities) can be very unreliable and expensive (I spent a couple of days last month trying to get hold of my wife on her mobile in Harare - it had coverage the whole time but the trunk network was down so she could only call some other Zimbabwe mobile numbers). On a corporate and government side, yes they've actually skipped a generation of technology, but I'm talking about small businesses and home users. The people who have the least to spend and need the technology most.

While the ISN format I believe should be standardized in presentation AND dialling, there is no law that says you have to follow the standard. You could create a local dialplan that makes users

As you say above though, this creates confusion. Shouldn't there be a recommended standard way to dial from phones without a * key?

re-format the number in a rotary-friendly way. Take these examples as my suggestions for a last-resort measure with a forward-adjusted run-length encoding of ISN digit length using zeros as length hints (since ISN subscribers nor ITADs can start with "0"):

ISN: 1234*256 turns into 000 1234 356
ISN: 2002233*329 turns into 000 2002233 329
ISN: 322*2593 turns into 0000 322 2593
ISN: 9934*10334 turns into 00000 9934 10334

Sorry the 000 in my example was my test ISN access code. The recommendation is 012 but once you add in our breakout code of 000, 000012 gets a bit long. This is another area where outside the US there may need to be some discussion or standardisation?

For example in most countries (+ = 00) (or 011 in the US). The ISN suggestion is to use 012 for ISN numbers but there's no direct equivalent of this outside the US. Typically non-US VoIP providers have been using 000 to signal a VoIP call as country code 0 is unused (ie 000 694 200 2233 would be my desk phone on the KCIP platform from most VoIP providers that use the Sipbroker codes).

I still don't see how I can tell where the users number ends and the ITAD starts, or vice-versa. Different systems will have different number lengths and it will be impossible even with just a few hundred ITADs to know the dial plan of every other system unless we register and lookup every extension in a central database - and that certainly won't work in remote areas?


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