Weak cell phone signal

Have you ever complained your cell phone could not get signal when you stay inside a building? I have such a problem all the while after moving to current apartment, if i want to have a clear signal, then i have to use my cell phone outside my house in balcony. So that's pretty ridiculous, and i certainly suspect there is no cell phone amplifiers at my staying apartment. Be honestly, my cell phone really seems useless every time when i am at home, just imagine what if i need to make an emergency call? Sure panic one...