Hi Andrea
We used a custom RFC call to a Destination, the Destination being a Queue which the PI system is attached to.
So in your action you call this custom function module, passing the information which is needed to generate the required SMS, you can either send as 2 fields or 1 string of information, that's up to you.
The result is that an entry is then visible in Transaction SM58 which the PI system will pickup and push to the SMS Provider.
Hope this helps
Regards
Arden