"Tom Holden" wrote in message
.. .
"The U.S. 1908 Dodge's Manual gives today's definition of 73 as "best
regards". Other Dodge numbers were 88 (love and kisses), 55 (lots of
success), and 99 (get lost, which was probably unofficial)."
"Dodge wrote this book for use by the students at his Institute of
Telegraphy in Valparaiso, Indiana."
http://artifaxbooks.com/afxrare/dodge.htm