Looking for a free SMS gateway that works with C# [closed]

Answer 1

You should just allow them to enter one more more email address. If people want an SMS they can enter the email address from their providers gateway. This would allow allow them to receive a message on a mobile/PDA style device without dealing with SMS.

Answer 2

Although I am not endorsing your methods nor this service, I did stumble upon a writeup of Zeep Mobile by ReadWriteWeb. If you are comfortable with them inserting ads into the SMS, this may be for you.