I've been trying out some headsets for my smart phone. Some of these are cheap, but got good reviews on Amazon. For instance, this Panasonic $9 headset (yes, I meant nine dollars), which requires a 3.5mm male to 2.5mm female adapter to use with a cell phone (as opposed to a cordless phone). I use headsets when talking on the phone at my desk to keep my hands free. I like the ones with microphones that wrap around right in front of my mouth, so that I need not disturb others when in my collaborative workspace. I've tried some other headsets too, including a bluetooth set that people complained about constantly.  I simply don't want people staining to hear what I'm saying.   I've found myself asking other how my voice is coming through when I speak on my cell phone (through the phone itself or using a headset).  People will give vague answers, such as "It sounds OK."   I've been wondering what my cell phone really sounds like on the other end.  I think I've found an answer.   I found a phone number that plays back your voice:  909-390-0003  .  That's all this phone number does.  When you call this number, you don't even hear a phone ringing.   But you can immediately speak into it and hear what you sound like.  Excellent.  Problem solved. I'm going to recommend it to others.  For instance, a friend of mine sounded all muffled.  I told him about this a couple years ago.  He eventually got a new phone and his voice quality immediately improved.  I wondered whether fuzz or dirt got into his phone's microphone.  Now his new phone sounds muffled.  I can't hear his consonants.  I'm going to give the test number to him, so he can hear it for himself. It turns out that my Panasonic $9 headset "sounds OK."    No, really.  It's a keeper.  It sounds great.