Any legit way to trace a cell phone number?

Someone is texting me sexual themed texts. They obviously know me as they mention my friends.

Is there any legit way to trace that cell number? I know there's a few pay sites out there that say they can get the owners name.

Thanks in advance.

Just embrace my advances

Backtracing is the only reliable way. 

Could be a texting/calling app. Not sure how easy those are to trace if it is. 

Bump for night shift crew

So....what do the texts say?.....unzips

okcaller.com can give good results

Text em "new number, who dis"

Send them a dick pic, wait for results.