[fa.telecom] Mexico "NPA's" on V&H tape

cmoore@BRL.ARPA (Carl Moore, VLD/VMB) (10/17/85)

I have continued reading area codes, prefixes, and place names
from a 1982 edition of V&H tape, and have now reached the end
of area 519.  Next are Mexican points with 6-digit NPA-NXX
combination starting with "52", the country code appearing in
your international-dialing page(s).  Such use of 52x is not an
area code in the usual sense of the word.  How many digits do these
Mexican numbers have after the "NPA-NXX" combination on the tape?
 
(Area code 706 is used for some points in northwestern Mexico,
such as Tijuana.)