A search on the number led me to her own website advertising her availability.  That is, it looks like she's doing this as an independent.  It could still be an agency but it doesn't look like it.

Noticing these posts are 2 years old.  Winter Jade is currently posted on Eros in Austin and Las Vegas.  I don't see any reviews for her on here so wondering if this is legit or perhaps could be a scam to get a large required deposit.  I would welcome any help/knowledge/advice on this.

Thanks!

I’m seeing her in Phoenix today.

I don't know about that specific ad but she is also on PC so she's legit. I love her scenes but she's been MIA from the scene for a few years now, unfortunately.