Hello,
We can use the below method to trigger SMS Alert without having any third party tool, If the Provider has the option of Submitting a message through HTTP(S) API
http://URLFORHTTPSAPI?user=USERNAME&pass=PAssword&senderid=SENDERID&mobile=XXXXXXXXX&lang=0&message=${N=SwisEntity;M=ComponentAlert.ComponentName}" of Application "${N=SwisEntity;M=Application.ApplicationAlert.ApplicationName}" on ${N=SwisEntity;M=Application.Node.Caption} is in a ${N=SwisEntity;M=ComponentAlert.ComponentAvailability} state
One action can trigger SMS to one recipient, you can add multiple actions as required.