从PHP电话号码发送短信

I'm a bit confused here and due to the keywords involved Google has not been much help. I want to send text messages from my website to users with cellphones via SMS. Sounds simple enough using things like 1234567890@carrier.com with php mail scripts right? Well one thing I've encountered before is that sometimes it sends an MMS(multimedia message) instead of a regular text message.

What I am trying to find out(using keywords in Google, send text message phone number php) is how to get a phone number for your website? I've seen sites that actually have a phone number linked to the site that you can receive messages from.

Example Facebook uses 32665 to send and receive messages on.

How do you accomplish this?

Is it any way possible using the 1234567890@carrier.com with php mail to strictly only send a text message and not multimedia?

Example php mail script using a phone number:

<?PHP
  mail("5558349324@vtext.com", "", "Test SMS", "From: RRPowered <test@rrpowered.com>rn");
?>

Also thanks to any help ahead of time, because I am really really confused at this point.

UPDATE: I just tried using the regular PHP mail functions to a phone number and it appears to cut the messages off at around 140 characters(I believe that is standard message size).

UPDATE 2: Before anyone mentions API like Text Magic, I am aware of those things, BUT I am wanting to build my own code instead of integrating someone elses API(if possible).