The pure SMS protocol does not allow including images or any other files in SMS content.

You can however upload an image or file to a publicly accessible location and link the URL pointing towards this image as a shortlink in an SMS. Some phones will even directly show those images as a preview when the SMS is received.

Viber does support direct sending of images and files if this is a prerequisite for you.
Contact support@sms.to for Monthly plan costs for Viber Subscriptions.