How can I get a signal on my Samsung Ultra Transform cell phone when I'm in my house?

You may simply be unlucky in the construction of your dwelling.
Sometimes switching off the 3G reception helps with voice calls..

There are boosters available (http://www.cellularsolutions.com/Direct_Connect_Mobile_Amplifiers.html). These are units that receive amplify and rebroadcast the signal they run around $200 US. I included one link there are hundreds just Google "cell phone signal boosters".