recipients list

Hi everybody, what I would like to have is the possibility to send sms to people without having to ask them to register to my site to receive my sms.
So I thought to this: create a flexible content type that alter the standard node form adding a phone field to it.
In this way you can create a very selective sms-blast-like module.
Think about having numbers stored in nodes instead of user profile. This would give the possibility to create groups, restrict access and send sms only to desired people.
Since now I've fiugred out a custom module that hold some of these features.