SSI is Sampling Survey International, a very big company.
There is a Wikipedia page about them :
https://en.wikipedia.org/wiki/Survey_Sampling_International
The website for SSI has a webpage says you can opt out of calls from them :
https://www.surveysampling.com/contact/opt-out-do-not-call/
* Email us at
[email protected] and include your phone number in the body of the email.
* Call 1-866-360-9563 from within North America or 1-801-379-4094 outside North America to be placed on our no-contact list.
* To speak to someone about the call you received, contact us toll-free within North America at 1-866-360-9678 or call 1-801-379-4094 outside North America.