@Misty The spark sampler is our first version of data plans, it was a feature that enabled text messaging and web browsing at the time. It is possible the 999-999-9999 you're seeing for text messages is because the feature is no longer compatible since we no longer provide text message details. I hope this helps.
I've figured it out. It's the number my doorbell cam is using to send me text messages when there is a motion detection and for whatever reason it shows up on my online account as spark sampler.
Thank you for the replies 🙂