KTEL Messinia AE is one of the 59 KTELs in Greece, which take care of the interurban bus connections in this country.
If you take notice you will probably see these greenish buses running down the road. They connect Kalamata to the big cities like Athens, Thessaloniki or Patras, but also with the smaller cities and villages of the prefecture of Messinia. The time tables are not quite as dense as you might be use to in other countries of western Europe but they make sure, you can get everywhere even without an own car, if you just take your time for it 🙂
Check their website for connections and dare to call them for checking about things not mentioned there (or even for the things mentioned there).