You might think Daryl Hall and John Oates would have a problem with their music being played for free through the crazy popular Callin' Oates service -- but it turns out the guys are thrilled about it ... so far.

For the uninitiated ... Callin' Oates is a phone number you can call when you have a "Hall & Oates emergency." Dial the number ( 719-26-OATES) press a button, and you have a choice between “One on One," "Rich Girl," "Maneater," or "Private Eyes."

The guys behind the site aren't affiliated with Hall & Oates at all, but a rep for the group tells us they're thrilled so many people are calling the number and listening to their music.

The rep tells us, "We had nothing to do with it and we're still trying to to process what the company's intentions are. But we're always happy when people are interested in our music."

Clearly there are some things they can go for.