A small VFR aircraft operating in the Dallas Area; clear of all controlled airspace; was contacted by an ADS Tower Controller who advised of a conflict while issuing corrective de-conflicting instructions.

Narrative

I was piloting an aircraft in the DFW area. We were following Highway 75 southbound; and we were about half a mile before the Collin Creek Mall VFR checkpoint for ADS. We were about two miles outside of ADS Class D. ADS Tower recognized our squawk code and; apparently; saw we were on a near collision course with another aircraft that was also outside of ADS Class D. Neither aircraft was talking with ADS Tower; however; we were monitoring ADS Tower and squawking. ADS Tower called us to let us know we had traffic at 3 o'clock. We looked but did not see the traffic and replied 'no contact' to ADS Tower. ADS Tower told us to make an immediate 360 left turn; which we did. As we came out of the 360-degree turn on our southerly heading; we did find the traffic now at our 9 o'clock and at our altitude. It was a high wing airplane; of unknown type; and it continued on its course to the east. There other aircraft never talked with us nor ADS Tower. We reported the other plane flying easterly to ADS tower and requested Class D transition southbound following Highway 75; and were given clearance from ADS Tower. Ten minutes later; upon exiting ADS Class D to the south; into Class B; we thanked the tower for the help with the near mishap. We cannot thank the Controller enough.