I just got 6 calls, one right after the other, from this number. No messages were left and the caller ID said "Unavailable." I am on both State and National "Do Not Call" lists. I have blocked all future calls from this number.
On multiple days I have received several (8 just yesterday & 3 today so-far). They accidentally left a message on my voicemail of their conversation. They obviously did not know they were being recorded. I also called the number back. From what I gathered they are a state funded environmental/energy conservation organization. They do not leave messages (on-purpose that is) and call back repeatedly. I am also on the do-no-call lists. The identification that comes up on caller-ID is "Texas" and "Unknown Name". I doubt the validity of this organization!