I received a missed call from the number 07011391968 which is also an odd looking number - appears to be something similar. The phone didnt ring by the way, and if it did, it must've only been for a split second.
I dont call them back, same as I rarely call any missed calls back unless its family - if its urgent, they'll call back
As for anything through our landline, we have *227# enabled to block all withheld numbers from calling through. We dont get any of these types of calls - I cant even phone home from work, so at least I know it works.