网络短信配置 - 邮件功能

I am using the code below for sending web mails and sms notifications. It works perfectly fine but I would like to ONLY receive the SMS when users choose “A” value from the servicerequired drop-down menu and also don’t want to receive SMS from 8PM to 5AM.

Any help is highly appreciated..

<form action="/thankyou.php" name="form1" method="post" >
<input type="hidden" name="curtime" />
<select name="servicerequired">
<option selected="selected" value="">Please Choose</option>
<option value="A">Replacement</option>
<option value="B">Architectural</option>
<option value="C">Commercial</option>
<option value="other">Other</option>
</select>
<input type="submit" value="submit" name="submit" />

and Here is PHP part

if ($_POST['submit']) {
       $to="myemail@mydomain.com";
       $sms="mymobilenumber@domain.net";
       $subject="Online Quote";
       $from = "webmaster@mydomain.com";
       $curtime = $_REQUEST['curtime'] ;
       $service = $_REQUEST['servicerequired'] ;
       $curtime = date("Y-m-d H:i:s");
       $headers = "From: $from
" .
       "MIME-Version: 1.0
" .
          "Content-Type: multipart/mixed;
" .
          " boundary=\"{$mime_boundary}\"";
       $message="message to email";
       $message2="message to sms";
       @mail($to, $subject, $message, $headers);
       @mail($sms, $subject, $message2, $headers);

ANS below - special thanks to @Dagon :

if ($_POST['submit']) {
           $to="myemail@mydomain.com";
           $sms="mymobilenumber@domain.net";
           $subject="Online Quote";
           $from = "webmaster@mydomain.com";
           $curtime = $_REQUEST['curtime'] ;
           $service = $_REQUEST['servicerequired'] ;
           $curtime = date("Y-m-d H:i:s");
           $headers = "From: $from
" .
           "MIME-Version: 1.0
" .
              "Content-Type: multipart/mixed;
" .
              " boundary=\"{$mime_boundary}\"";
           $message="message to email";
           $message2="message to sms";
           @mail($to, $subject, $message, $headers);
if($_POST['servicerequired']=='A' && (date("G")>5 && date("G")<20)  ){ 
           @mail($sms, $subject, $message2, $headers);
}

if($_POST['servicerequired']=='A' && (date("G")>5 && date("G")<19)  ){ 
//SMS STUFF
}