Text Messaging *67

So I called a number a few times or so using *67, I never added it to my contacts. Now today I texted the number, it automatically adds *67 before the number. I can get the texts to go thru only if I delete the thread after each message. I even tried deleting the texts and just replying to one of theirs, it still changed the number back at the top. When I receive a text from them, it comes up as their number but the thread has the *67 and thats what it sends to so I have to keep deleting it or I get a text saying the address was invalid. It was never added to my contacts so I don't see why it comes up like that. I've used *67 before with other numbers and later texted and never had this. HELP?!