Samsung Transform

All phones have a speaker hole somewhere that can be covered up.

Most phones put it on the side, bottom, or back as a safety feature, so you don't blow out your eardrum holding it up to your ear when you don't realize it's in speakerphone mode.

I'm surprised to hear you talk about you holding it in your hand. Most people don't use speakerphone while holding the phone. In fact, many phones refer to speakerphone as "hands-free" mode, specifically because it's designed for when your hands are not free. If your hands are free, why use speakerphone? Why not hold it to your ear?

If the speaker's on the back, the question is whether setting it on a table blocks the sound. On most good phones, there's a special bump, etc. to raise the back off a hard surface just enough that the sound isn't blocked. There are some poorly-designed phones that dont have this, though.