Send Email to Mobile

["Marcelo Ferrufino Murillo" <marcefm@xxxxxxxxx>]

Hi guys, I have a script that send emails to mobiles:

<?php
$subject=$_REQUEST["sb"];
$nmobile=trim($_REQUEST["nmobile"]);
$message=$_REQUEST["message"];
$header="From: sms@xxxxxxxxxxxx";

//Bolivia providers
switch($nmobile[1]){
        case 0: $company="@viva-gsm.com"; break;
        case 1: $company="@entelmovil.com.bo";break;
        case 2:
        case 3: $company="@movil.com.bo"; break;
        case 6:
        case 7: $company="@tigo.com.bo";break;
    }
   $number="591".$nmobile.$company;
   if( @mail($number,$subject,$message,$header))
       echo "Message sent";
   else echo "error";
?>

And this is the message in a mobile:  nobody@xxxxxxxxxxxxxx ................


I don´t know why appear the address nobody@xxxxxxxxxxxxxx the address must
be: sms@xxxxxxxxxxxx, could you help me please, thank you