For what it's worth, you can use Google Images to search for other instances of the photos. Here are the hits (other than those related to the Backpage ads or other ads from the same lady, mostly in NH and ME):
 
First photo "Good_One_17":
bonton.co.nz/wellington/courtesans.html‎ - this website appears inactive.
 
Second photo "Good_One_18":
none
 
Third photo "Good_One_19":
none
 
Using the regular Google against the phone number brings up a few interesting hits (first one is a review). TER does not allow me to post with links to ads/reviews, sorry...
 
No huge red flags in my opinion. I am really tempted to TOFTT but will defer to the perfesser...

She had been running the same ad in both Maine and NH BP up until just before Christmas then disappeared. At that time she was based in Southern Maine. Same photos. Incall only.

I recognize the pics, believe it is the same woman who went by JJ. something. I think there are reviews. I have never seen, but I recall mediocre reviews