There are many sms services like mycantos or 160by2 on the internet. I do not know how safe they are. I mean I would be wary of sending messages through these. AFAIK, they gather the numbers you send smses to and then send advertising/spam messages to these.
try way2sms.com
Yup
160by2
sms7.in
way2sms
indyarocks
there are many.