Another way would be using telepathy.
This is the one I've been trying to explore and think should be more appropriate as it allows:

a) step up one abstraction above phone implementation
b) use common interface for SMS and IM messages
c) it automatically adds messages to the comhistoryd - visible in messaging centre.

There was an issue though that only one consumer could be attached to Tp::account as it uses static member internally. However it seems (partially) this was fixed.
nemo-qml-plugin-messages is an example how it works.
Here's an example - https://talk.maemo.org/showthread.php?t=95876
You can get directly to the channel for the phone as it is hardcoded mostly (ring/tel/ring), but IM accounts should be properly discovered based on notification data (from that base64 encoded VariantMap in the x-nemo-remote-action-default) using appropriate telepathy management interface.