I found an interesting page:
http://www.llv.li/amtsstellen/llv-ak-nummerierung.htm

From the formal point of view the entire +423 663 is not considered as shared revenue/premium rate numbering range.

But what about that e.g. : http://www.new7wonders.com/index.php?id=400
The number they use for voting i.e. +423 663 90 02 99 belongs to: Mobilkom LIE AG +423 663'900?000 - 663'999?999 is "Mobile network number allocation for international Services" just like UM range
(http://www.llv.li/pdf-llv-ak-mobile_...0032006_en.pdf)
But this 900 inside... :unsure:

Voipfone considers the whole 423663xxx range as personal numbering/premium and not as mobile. The 423663900 are also used for premium rate services (daopay and others).

I suppose this is because it is difficult to distinguish between +423663100 and +423663900 some providers consider the +423663xxx as premium

In my country the telecom organisation charges all calls to +4235, +4236, +4237 higher
(0,75 euro/min)

Difficult to distinguish? Are you kidding?

I meant that they do not bother to distinguish. Normally premium rate numbers are distinguished in the first code after country code, e.g. +449, +309, +49900, +3290, etc. In L. this is not the case since after +423663 the remaining six digits can belong to a mobile and a premium rate number..... I already mentioned that voipfone does this clearly. It considers all the range +423663 as personal/premium and charges it slightly higher than mobile phones in the country

The question is what "international services" really means. It might be either MVNO like United Mobile, or some shared-revenue (aka premium rate) numbers, or possibly something different (e.g. high-rated "personal" numbers which forward to "real" mobile/landline number somewhere in the world) or something else....

My landline operator despite its undoubtely horrible rate to Liechtenstein mobiles (about 1 EUR/min) also has the following rates:

Liechtenstein (VAS) about 2.70 EUR/min

and:

Liechtenstein (Int.Mob.Svc) about 1.70 EUR/min

I'm afraid that UM may be the latter case. The operator doesn't provide numbering ranges of course :P. Anyway, even their basic rate to Liechtenstein mobiles is crazy enough in order not to use this operator for calling UM.

The fact that most operators increase substantially their rates to UM (not only in Greece) supports my arguement about the difficulty in differentiating in such a small number range. Also you may add to that that Mobilkom asks for high incoming rates to connect to such numbers. So add these and you have some answers ;)

In some sense it's the answer what you said. But I suppose that some premium rate (in its common sense like lotteries, "sex lines" :) etc ) +423 663 numbers existed before releasing Riiing to the market. So, why then were rates to Liechtenstein mobiles similar to rates to other Western European mobiles?

Are we going to see the samething happen with IOM numbers, etc.

You cannot be sure as to when exactly these numbers were released. So you can only suppose...... ;)

No way with IOM numbers. As there always will be reasonable cost when calling from UK.http://g.zpravy.cz/u/disk/zadek.gif