>>update: I've just found that my provider has such a service with just two rules on how to get the email address from the number. Tried several times to send myself a message and it wasn't delivered - got a bounce email.
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>You have to unable your cell phone to receive that type of message. But then again it would be a controlled environment. Ie company to employee.

I thought it was enabled by default... or that the email would arrive as an SMS. I did this once while in the US, and it worked there just like that: I got an SMS.

Still, that only solves the problem of how to send a message when you know the provider. Most of the time you only have the phone number, and that's where these services kick in - they have that information and they sell it as a service.