Someone with a random number is texting me?

Okay so i know who the person texting me is. I just want to know where he is texting me from, because he is really annoying and won't stop texting me when i've asked him numerous times. He keeps telling me to stop talking to my friend sarah because he doens't appreciate it. He thinks they are dating but they really aren't. The number is 14100000--, the last two digits change with every text in numerical order. Ex: 1410000074, 1410000075