It sounds rather too speculative to me, and the termination and subsidy issues would be on rather different scales if indeed they are the reason.

I understand, perhaps wrongly, that it was when AT&T, not the taxman, found itself with multi-million dollar bills that those Iowa numbers came under scrutiny, though it was presumably federal policy to mandate the subsidies.

Manx is not simply a poky regional operator, but part of a larger firm. I doubt that the person you met has detailed knowledge of any cross-subsidies between the companies and the Manx and UK governments, and whether the regulators have it on the agenda. Ofcom don't seem quick on reducing de-facto subsidy due to the higher termination charges of 3, didn't intervene on 07744 callthough number issues, and given the pig's ear that they have been making of shared-revenue numbering issues for several years, I don't think we'll see fast progress on something more complicated.

I don't think your case 2b is likely. Anyone who can program a dialplan to filter and select carriers to use can distinguish between different phone number prefixes. Some Asterisk pundits do this at home for themselves, but on a global scale all retail call providers will be doing something similar, including a few mistakes we may or may not be aware of. Some carriers can and do have separate rates for the different UK mobile networks.

For another example, some cheap providers have slightly different tariffs for US landlines and mobiles. It is possible to tell the difference, but whether they do so correctly I don't know.

There is a callback company in the UK that still has a rate of 2 pence a minute from UK mobile to UK landline, probably still a promotional price, as their sister companies are in the 4 to 8 pence range. Usually the callback has come back with no caller ID, but I have seen about 5 Nanjing Chinese gateway numbers.

If Finarea could do it on a bulk scale, maybe we can try having a look there too. Is it far-fetched to use China? Well, I recently set up a VoIP account in Brazil, but I have no idea if I will ever go or even phone anyone there.

Andy...

I'm really not sure how one can distinguish between US landlines and US mobiles....they have exactly the same range of numbers and the FCC does not allow discrimination for one service over another.

Let me give you an example....area code 917 was introduced in NY and originally it was to be just for mobiles and pagers to relieve some of the pressure on 212 and 718....the FCC ruled this practice was illegal and now there are many landlines in the NYC area with area code 917...all the distinctions seem to be blurring....you can have a 347 area code number for your landline or for your mobile or for your voip number (the only thing difficult to get for any of these in the NYC area are 212 numbers!)....or am I missing something?

Matha531 I was also wondering how a voip company could distinguish US landlines from mobiles....

Actually ...

Try a few searches on the www.numberingplans.com website, that Przemolog first recommended to us

http://www.numberingplans.com/?page=...is&sub=phonenr

- mess around with the next 3 digits after the area code, eg the 555 of common examples - you will find provider information comes up for valid results, and some of these are mobile phone companies

I rather doubt that many companies would actually bother to keep and search such databases to determine tariffs or for any other reason, but it is hypothetically possible

Here are some of the 917 allocations you mentioned
http://www.numberingplans.com/?page=...ent_page=12288

...which leads to the question do the US mobile carriers use termination fees the same way European and other places do...in other words does it cost a provider more to dial into a mobile number than to a landline or other number in the USA? I don't think so.

I've seen one website that had slightly varying rates for different area codes in USA, but can't remember where it was, and I don't think there were exchanges listed within area codes. I expect those Iowa numbers were a bit higher.

Some of the Betamax VoIP companies say they have differing retail rates, but their wholesale arm VoiceTrading has the same for both

http://backsla.sh/betamax

- but as I suggest, how likely is it they would bother to look up a table with over 130,000 elements?

Highly unlikely I must say......

I think the area codes that have different rates are those in Alaska and Hawaii sometimes....

Great job on a cross-carrier rate chart!

Suggestion...can you post the .xls file on Rapidshare or here(Rapidshare works OK, can't retrieve the Yahoo file for some reason) so we can add to it? Some people may want to figure out what the termination rate is to different countries or add other carriers.

Also possible to post here by zipping the file (bigger uploads allowed for compressed files than raw spreadsheets or PDF's).

Also think minor blooper on United Mobile direct dial outgoing from Canada to US (rate shown I think is incoming rate which you wouldn't get unless you used Callback World for a double call back).

The UK government doesn't have anything to do with Manx Telecom (apart from anything else, MT is now a division of Telefonica of Spain). Nor does it have any direct control over phone systems in the IOM, that's the job of the Isle of Man Communications Commission.

The IOMCC does have to deal with the UK's Ofcom for number ranges, much like countries like Caymans +1 345 have to deal with Nanpa, because the country code is shared. But Ofcom doesn't control the rates or how the numbers are used.

I don't think there's any reason other than lack of will (or number availability, or regulation) why any UK based mobile company couldn't do something similar to what is being done with Manx number ranges. It costs so much to call any UK mobile number that there is plenty of room for the forwarding/roaming cost.

Indeed many of the UK 0844/0871 etc international callthrough numbers like pennyphone.co.uk (similar to the Iowa numbers) do already forward calls internationally at rates to the (domestic) caller that are lower than calling UK mobiles.

There's no loophole or subsidy being exploited anywhere for the Manx numbers - they are simply using the high incoming charges to "UK" mobiles to pay for the forwarding/roaming. Same could be done with UK numbers, or Jersey/Guernsey.

On your last sentence - I'd be amazed if any carrier charged the Caribbean at US rates, other than as an initial error. With all the premium rate numbers there they wouldn't last long...

Thanks for doing the chart, I'd be interested to see it, but I currently can't reach the chart with either link.