SMDS addresses are E.164 addresses, or telephony addresses. In the USA,
SMDS addresses are taken from the North American Numbering Plan (NANP),
which is consistent with E.164 addresses and is administered by Bellcore.
You should contact whoever administers the telephone numbers for Mexico.
You might contact the administrator of the NANP for guidance on who
administers Mexico's address space. His address is...
North American Numbering Plan Administration
6 Corporate Place, PYA 1G-278
Piscataway, New Jersey 08854-4157
(908) 336-3293 FAX