Recommendation U.7
NUMBERING SCHEMES FOR AUTOMATIC SWITCHING NETWORKS
(former CCIT Recommendation E.7, Geneva, 1956)
	The CCITT,
considering
	that with fully automatic working between subscribers in the international telex service it is desirable to envisage the possibility:
	a)	of routing traffic over the appropriate international trunk route where more than one such route exists between two countries;
	b)	of enabling the appropriate tariff to be determined automatically (in the originating country), even if the destination country is divided into several tariff zones,
unanimously declares the view
	(1)	that subscribers' national numbering plans should be systematically arranged;
	(2)	that, where more than one international trunk route exist between two countries, the corresponding geographical division and hence the appropriate point of entry should be identifiable by examination of the initial digits of the called subscriber's national number;
	(3)	that, where a multiple tariff scale exists, the different tariff zones should be identifiable in the originating country by the initial digits of the called subscriber's national number;
	(4)	that the number of initial digits to be examined should be limited, preferably to one, but in any case should not exceed two. When a single digit provides the discrimination it will usually be the first digit, but, where the subscribers' national numbers have a uniform initial digit (usually 0) to permit discrimination on internal calls, the following (second) digit should be used.
	Note – The attention of Administrations (and recognized private operating agencies) is drawn to the considerable technical advantage that would result from the adoption of a single tariff between two countries.