Virgin Mobile could never get service in my house. I thought it was my phone.
New phone still same problem for several years. Informed Virgin but they could not give a reasonable answer. They relied on Mobile Coverage Checker, which supposed to show you good or poor signal areas.
Ask friend's, family, neighbours which service provider they use and ask to borrow their phone and move around your home. This way you can check signal coverage. It worked for me seeing the evidence with my phone and a friends phone side by side...one with full signal the other zero.
So I changed to a new service provider...now I have service throughout my home. Glad I did. Alternatively, search the market for Mobile Phone Boost in the home.