Just another one of those “unsolicited solicitors”! I'm not sure who it is (nor do I care), but they won't be bothering me again - sort of...
I don't believe that 'do not call' lists stop these people... There is a simple solution! Now I have them on my personal "do not ring" list! I save the numbers from similar type calls to my phone book under 'zz telemktr 01, zz telemktr 02', etc. and select their ringtone for 'no ring'.
Since you can't prevent them from calling, you can stop your phone from ringing when they do call. I have done this with several of these type numbers. Once they call me, I put them on my own kinda “do not ring” list – works great! :)