If in doubt - do your the obvious research. Google the phone number (with and without spaces*) - I found a 'Tanya' with different photos.
Also use reverse image searching in Google Images and Tineye.com. Right click the image and get the URL and then use the reverse image searches to see where else those images my be online... often, which porn site they have been taken from!
Never part with money unless it is in person!!! :-)
* if you search a term with " " for example "big bottomed girls" google will only show results where EXACTLY those words, in that order are in the page... so with phone numbers, use the quote marks when using spaces e.g "01234 567 789" or it will show result for pages that have some of the numbers or all of them in different orders... because it treats strings of numbers like separate words.