I signed up for Google Voice. Mostly I wanted to see how it works. I paired it with my cell phone, but I haven't used it since.
Meanwhile, a friend of mine replaced his cell number with his Google Voice account. I sent him a text from my cell phone to his Google Voice number a few days ago.
And the text showed up in MY Google Voice account too.
I tried it again to make sure. Screenshot is below (phone number is obscured to protect my friend):
Why is the message I sent from my phone to my friend's Google Voice account appearing in my account? That means Google decided that messages received by and sent from his account should appear in mine too.
To be clear, I didn't use my Google Voice account when sending or receiving the message. Google looked at the phone number, matched it up with my account, then stuck it in my inbox. To date, the only messages in my Google Voice inbox are the welcome message and the texts to that person.
This is a ridiculous security and privacy hole. If you swiped someone else's phone for just a minute, you could attach it to a Google Voice account then receive all texts between that person and any Google Voice user.
I've been a big fan of Google's past products, but this is the first time I've ever been freaked out by something they've done. I hope Google realizes the flaw here and fixes it quickly.