SMS sending through free gateway

Yeah, or you could use the gateways as provided by the wireless carriers themselves, as then it's as simple as sending them an email with PHP's mail function.

Where (Number) is, you must include their 10 digit phone number. So that means that you must include their area code.

AT&T (Number)@txt.att.net

T-Mobile (Number)@tmomail.net

Sprint (Number)@messaging.sprintpcs.com

Verizon (Number)@vtext.com OR (Number)@vzwpix.com

THE Code you are using is totally outdated. Way2sms change their way of authentication. If you want to use new code then here is solution : http://ritesh-chandora.blogspot.in/2012/02/php-code-for-sending-free-sms.html this blog will provide new way of sending sms easily.