If you set up your survey accordingly and work with a proper SMS gateway provider which supports sending SMS based on emails sent to their service, you don't need a plugin at all.
We have just successfully finished a project at which we have used
messagebird.com
as SMS gateway. When setting up the process of sending the invitations correctly, you can directly send invitation emails to the service which turns the emails into SMS.
This allows to
- use the Limesurvey email invitation feature for sending SMS
- use the email templates to define SMS sender and SMS content
- use a cronjob to schedule email sending
Regarding the later: For a medial research project we are sending a new SMS weekly so people can file a new response reagrding their current health status. We also added some additional code to our email cronjob to re-set some participant details like "uses left", "completed" and the like so they can start a new data set once they received another invitation by SMS.