Here you go. Create an account at 160by2.com and install php on your system.

sudo apt-get install php5-cli php5-curl curl

Paste your number and password where i've mentioned and run this script:

<?php

echo"Phone: ";$phno=trim(fgets(STDIN));

echo"Message: ";$msg=trim(fgets(STDIN));

echo"Message Length: ".strlen($msg)."

Sending...";

$yournumber=''; //your number inside the single quotes

$yourpassword='';//your password inside the single quotes

$cur=curl_init("http://160by2.com/re-login");

curl_setopt($cur,CURLOPT_POST,1);

curl_setopt($cur,CURLOPT_POSTFIELDS,"username=$yournumber&password=$yourpassword");

curl_setopt($cur,CURLOPT_COOKIESESSION,1);

curl_setopt($cur,CURLOPT_COOKIEJAR,"cookie");

curl_exec($cur);

curl_close($cur);

$cur=curl_init("http://160by2.com/SendSMSAction");

curl_setopt($cur,CURLOPT_POST,1);

curl_setopt($cur,CURLOPT_AUTOREFERER,1);

curl_setopt($cur,CURLOPT_COOKIEFILE,"cookie");

curl_setopt($cur,CURLOPT_POSTFIELDS,"mobile1=$phno&msg1=$msg&action1=sa65sdf656fdfd");

$x=curl_exec($cur);

curl_close($cur);

echo"

Sent!";

Save the script as sms.php.Then on terminal run php sms.php

DONE!