Smsti.in allows you send message of complete 160 words and without any ads.There message service is very fast and you can even check the delivery reports of the sms that has been sent.
They provide their sms services for Indian Mobile numbers only.
Seasms allows you to send messages all over the world.This is the only free Sms service that I found which all allows you to send worldwide messages anonymously.
They also provide 160 character support for SMS.
Spicesms allows you to send sms only in India with 130 character support for sms.They service is very fast and sms are delivered instantaneously
Bollywoodmotion is one of the best sms website as you can send sms upto 500 characters long.
They do not include any ads into your message and messages are delivered in real time.This service is available only for Indian mobile numbers
If you know any other sms services that allows you to send messages without registration then do share with us by commenting.
NOTE:- Don’t send abusive messages to somebody using the above site as you can be traced .