Utilize the [keys/claim](https://matrix.org/speculator/spec/HEAD/client_server/unstable.html#post-matrix-client-r0-keys-claim) endpoint to claim a key, then [create an outbound session](https://matrix.org/docs/guides/e2e_implementation.html#starting-an-olm-session).
Utilize the keys/claim endpoint to claim a key, then create an outbound session.