Ecco un po di siti che permettono di mandare sms gratis :

https://zyb.com/

http://stepsms.com/

http://www.smstxtbox.com/web/

http://www.junglesms.com/

http://50sms.com/

www.devinosms.com

http://gsms.se/

http://www.themobiweb.com/en/sms.html

http://my.phonegnome.com/

http://sms4u.biz/signup.php

http://simsor.com/register

http://www.mobik.com/mobik/client/

http://www.smsdiscount.com/en/index.html

http://4usms.net/

by codehack.it 

ENJOY!