On April 23, 1913, the International Teleconmmunications Union assigned Mexico the call letter range from XAA to XCZ. However, Mexico did not use this call letter allocation in assigning call letters to the first commercial stations. A list of Mexican stations from 1925 shows one station with an odd call (see 24A). From other sources, this was apparently issued as an experimental amateur call. The remainder of Mexican commercial stations were issued three-letter calls beginning C generally followed by Y or Z. This block of letters was unassigned to any country in the 1913 allocation, but in 1927 the CZ block was assigned to Monaco (the CY block was still unassigned). It should be noted that there are books that claim that a 1924 conference gave the CYA-CZZ calls to Mexico, but I have seen no evidence that this was actually the case. In 1929, new international allocations became official, and Mexico was assigned the call letter range from XAA to XIZ, effective January 1, 1929, and the Mexican government chose to use XE- and XF- prefixes for commercial broadcasters. Up until then, Mexico continued using the CY- and CZ- calls, and the change apparently did not take place immediately at that time, as C-prefixes are still shown in a listing dated January 31, 1929; however it is possible that this listing may have been outdated when it was printed. The exact date of the change is not clear; a RADEX guide dated April 1929 lists Mexican stations with the old call letters, but it carries a letter from a reader that station CZE had been changed to XFX, implying that the change was made prior to April 1929, and the Radio Service Guide issued by the United States Department of Commerce, in fact, shows the new call letters in its March 30, 1929 issue.
Currently, Mexican AM stations are assigned call signs beginning XE, with anything from 1 to 4 additional letters. Not very many 6-letter call signs are in use, but because of the large number of 5-letter call signs, the XE section is broken down beyond what is otherwise the case for this Wiki. FM and TV stations have an XH prefix, except that some stations with earlier-assigned XE prefixes and -FM or -TV suffixes have been grandfathered and still use these calls.
- ↑ Early Mexican Broadcasting, by Marvin Alisky, The Hispanic American Historical Review, Vol. 34, No. 4 (Nov., 1954), pp. 513-526
- ↑ (2004) Mexico: An Encyclopedia of Contemporary Culture and History. Santa Barbara, California: ABC-CLIO, 426. ISBN 978-1576071328.
- ↑ Radio Service Bulletin, United States Department of Commerce, #144, March 30, 1929