That's still a man in the middle coordinating the payments (mpesa, etc...) and essentially holding both sides of the transaction. When you send money to somebody with mobile money you're sending it to the mobile network operator who then let's the other person know so they can move the money to somebody else (or cashout or leave it there).
It's not really a federated system because you can't for instance send money from mpesa in kenya to a different provider in uganda.
