Sometimes you can figure it out just by putting it in a google search because they may have put it out in the interwebs space before..like in a classified ad. I know there are reverse directories, just not sure which are the best/most reputable.

Spokeo is pretty good, but you have to pay for it. It's not always up to date. I use it at work to find people.

You can put the number in the search line on Facebook and it will show who's facebook is linked to that phone number. It works most of the time now due to smart phones and people having their social media linked to their phones.

reverse phone look up. It will tell you if it's spam, a business or who the owner is.

Is it coming through as an actual number or a weird one like a promotional text would come through? For example 131-442 or something of that nature. I know there are quite a few sites that pings the number doing the texting of multiple towers to disguise the origin of the number.

If you get no luck via google, depending on the state and the nature of the texts you can file a case with the PD and if the texts are threatening or vulgar of any kind they can try and trace for you.