BPO means Business Process Outsourcing; I'm assuming you mean the same thing. I would imagine that "non-voice" BPO jobs would be ones that do not involve communicating by voice with the customers....
If you mean that your voice stops vocalizing when you still wish to speak, then you should see a physician. This may be a simple muscle problem, or it could be serious.
This looks like a punning reference to the phrase "sotto voce" ( below the voice), meaning "spoken in an undertone." Blotto is a slang word for falling-down drunk, so it might mean "speaking like a...