The telecoms company’s German company has released a documentary-style online film as part of its Vodafone Firsts campaign.
It shows the emotional reunion of Manuel Segovia, 78, and Isidro Velazquez, 72, who are the two remaining speakers of the Ayapaneco language.
The pair had not spoken for years after a fight, leading to fears that the language would die out.
With Segovia and Velazquez’s help, Vodafone has created a mobile site with a dictionary for the language.
People from all over the world are urged to "adopt" an Ayapaneco word, to watch tutorials by Segovia and Velazquez and to record videos of themselves online saying Ayapaneco words.
Ayapaneco words and phrases such as KO'O, which means "goodbye", and MAA'K, meaning "to fish", can be "adopted" on a website at Ayapaneco.com.
The project aims to show how technology can be used to ensure the language "lives on forever".
The film was made by the German creative agency Jung von Matt/Alster. Götz Ulmer was the creative director.
Vodafone has also worked with the people of Ayapa village in Tabasco, Mexico to set up a language school for children to learn Ayapaneco.
A festival to celebrate the opening of the school marked the first time many people heard the language being spoken.
Gregor Gründgens, the brand director of Vodafone Germany, said: "This First demonstrates how language – one of the oldest forms of communication – can be given a new lease of life thanks to modern communications - mobile technology and the internet.
"Technology can enable some amazing things. In this case, helping to prevent a language from becoming extinct."
Vodafone worked with Stanford University linguistic anthropologist Professor James A. Fox on the project.
Fox said: "We have, in cooperation with Manuel and Isidro, compiled a dictionary for this language, covering the main areas of life.
"With Vodafone's help, this dictionary is now available online and will make a crucial contribution to help rescue Ayapaneco."