Receiving calls from GVDM that cant be traced when I contacted them

I received a "missed call" from a cell number from GVDM Attorney's Incorporated earlier today. I phoned them back and the lady at reception said that nobody called me but she will remove my number from their system. My question is, If nobody phoned me from their cell number, how is it that I received a missed call from them and what is my cell number doing on their system? She asked for my surname, without any results. Later on I received another missed call from them with the same results. This time I was told that she will escalate the request to the IT department to remove my number from the system. Again, my question is, What is my number doing on their system?

They don't supply any email on their webpage