Can you identify a voice that pes through a voice changer?

If you record a phone call or watch a video where the person has changed their voice either through a dedicated voice changer or through computer software, can you change the voice back to their normal voice? I see criminals in movies talking over these voice changers and people on YouTube using funny voices and I am just curious if you can easily get the original voice from these recordings, or does it make the person unidentifiable?