AT&T free messaging gateway.
rogers Canadian Messaging, Rogers, 123 char.
clearnet.com messaging, 280char. (click on "send a text message")
GSM regional nets:
Most messaging systems have a limit on the number of characters you can send. To write the most in the limited space we recommend to capitalize every second word, and write the words withous spaces. That way you save space and the text is still legible. Example: