How can I send email to a cell phone as a text message if I don't know the phone's carrier?

I’m aware that if I know a person’s cell phone carrier, I can send an e-mail which they will receive as chat. I have this thought in the back of my mind that some gateway services at one point allowed you to specify __I don’t know the carrier__ and they would figure it out (or perhaps make a stab.)

Anyone know if this is possible?