I received a text message from this number it says:  thanks for calling Plantronics Vocalyst! To activate your free one year service go to www.plantronics.com/vocalyst.  I went directly to the Plantronics website and set a message to customer service asking if this came from them.

yES TODAY I RECEI VED A MESSAGE SAYING THANKING ME THAT I PLACED A CALL TO PL;ANTRONICS,M I TOO OWN A PLANTRONICS DEVICCE AND DID NOT MAKE SUCH CALL

I got a call from this number, and it said it was Plantronics. They thanked me for recently contacting them (I didn't) and asked me to sign up for a free 1 year service deal and provided a link. Again, never contacted them, but the name is the manufacturer of the bluetooth piece I use with my cell phone. I'm not sure if this is just coincidence or perhaps I did something with that.