You can ask your audience to send in their questions via SMS to your account's dedicated number. These questions will appear in the Feedback section if you have an active poll, and will be added to the list of responses for open ended and word clouds.
Here's an example of a question received in an SMS and stored in the Feedback section
When your audience submit questions in SMS, they will receive a confirmation text that their feedback has been received.
Here's an example of responses received for an open ended question.