Is there a way I can text message any one or more of my friends' cell phones from my computer?

I’d like to be able to do this for free, without knowing each person’s cell phone provider, without requiring my friends to join anything, without requiring me to have a phone on each friend’s network (though I have Verizon), without advertising, and preferably more than one addressee at a time. This is not for spam purposes. If I have to submit a CAPTCHA each time, I can live with that. It would be nice to be able to do both SMS and MMS messaging. I only need to do this within the United States.