Talkers.

This is coolbert:

"American military officers such as Rufus Ingalls or George Crook would sometimes send messages in Indigenous [American Indian] tongues to other officers whom they knew shared their expertise in the language."

Before there were the code talkers there were the code talkers. And continue to be so too.

Courtesy the wiki and the tip from the Internet web site Strategy Page the history of the code talker as not known to me.

"A code talker was a person employed by the military during wartime to use a little-known language as a means of secret communication." 

The Navajo American Indian code talkers most persons conversant with the history of the Second World War are familiar with. Radio communication secured.

Consider also languages as used by code talkers and not necessarily so by American military forces.

1. Basque.

"In November 1952, Euzko Deya magazine reported that in May of that year, upon meeting a large number of US Marines of Basque ancestry in a San Francisco camp, Captain Frank D. Carranza had thought of using the Basque language for codes."

PROPOSED BUT PERHAPS NEVER IMPLEMENTED!

2. Nubian

"In the 1973 Arab–Israeli War, Egypt employed Nubian-speaking Nubian people as code talkers."

3. Welsh

"A system employing the Welsh language was used by British forces during World War II, but not to any great extent. In 1942, the Royal Air Force developed a plan to use Welsh for secret communications, but it was never implemented. Welsh was used more recently in the Yugoslav Wars for non-vital messages."

4. Wenzhounese.

"China used Wenzhounese-speaking people as code talkers during the 1979 Sino-Vietnamese War."

5. Hungarian. American Civil War.

Hungarian immigrants to the USA written messages in their unique language a form of secure communications at that period of American history. New citizens USA serving the cause of Union and their new country in a manner hardly anyone could have ever anticipated.

Thank you NSA for # 5. You learn something new everyday.

coolbert.