Mobile phone at home

Ever since I moved into this apartment almost eleven months ago I've had problems with my mobile phone's signal which is incredibly weak.  There's a mobile phone mini base on the corridor ceiling near the entrance to my apartment, but it's from the competing mobile carrier, not mine which is the largest company in the country.  So it was kind of annoying cause as a result of that I always had to leave my mobile near the window, and even then I'd have a hard time talking on it.

But today somehow the signal got a lot stronger and I can have a very clear conversation even from the room that is farthest away from the window!  It's not an illusion, I already talked about three times today from that room, and the three times it was very clear.