According to Wikipedia: "The Elder Futhark (or Elder Fuþark, Older Futhark, Old Futhark) is the oldest form of the runic alphabets. It was a writing system used by Germanic tribes for the northwestern and Migration period Germanic dialects. Its inscriptions are found on artifacts (including jewelry, amulets, tools, weapons, and runestones) from the 2nd to 8th centuries."
A few notes:
There are no numbers. Rather, numbers are just spelled out.
And the people who used this alphabet weren't big on punctuation, so no commas, quotes, apostrophes and the like.
While there is a space bar provided on the keyboard, they either let all the symbols run together or words were separated with a dot (also provided on the keyboard). Instead of a period to end a sentence, you can use the two dots symbol (one more time, also provided on the keyboard).
The keyboard is laid out in three groups of eight keys. Each row called an aett. This seems to be how the runes are often displayed.
Again from Wikipedia: "The earliest known sequential listing of the alphabet dates to 400 and is found on the Kylver Stone in Gotland."
The more you know...
Also, if you don't have an unlimited data plan, standard usage rates will apply.
Both sender and recipient need to download the app to get the messages.