Office Room causing dropped calls/no bars

[3DArtwork]

Beginning back in June and progressively getting worse, I am unable to receive or send a phone call using my Nexus 7.  I have updated it completely.  If I leave the building and travel approximately 100 or 200 yards, I have no problems.

The building itself has suddenly began to negate my phone signal.  I have checked with the owners, and no structural change has occurred this year that might cause it.  I have not changed any electronic devices around me that might cause it.

I am unable to use the phone period while at work, and I have missed numerous important phone calls because of it.  I will have to switch phones (and perhaps providers again) if I can't find a solution.

Before this began a couple months ago, I had NO PROBLEMS for the past TWO years working in the same room.