Failing to set SMS notification on PR4100

I wonder if anyone succeeded to use ( and is currently using ) the SMS notification?

I tried to configure the SMS notification, but each time I click on the “Test SMS”, it fails due to “Error”.
What I was able to check is that the PR4100 doesn’t try to send out the request, so the issue is not the SMS backend service.
The PR4100 uses a command line called /usr/sbin/send_sms.
When I try to run it manually ( with the same argument as the setup process ) I’m getting a failure due to wrong arguments, and it prints the help menu.

Thank you,