OSTicket is a decent piece of software for customer service. I upgraded to PHP 5.3 and had some problems because they are trying to keep it working all the way back to PHP 4.

Here is a patch to fix the eregi_replace deprecated errors.

diff --git a/osticket/include/class.format.php b/osticket/include/class.format.php
index 6cbb414..0380268 100644
--- a/osticket/include/class.format.php
+++ b/osticket/include/class.format.php
@@ -78,10 +78,10 @@ class Format {

     //make urls clickable. Mainly for display
     function clickableurls($text) {
-        $text=eregi_replace('(((f|ht){1}tp(s?)://)[-a-zA-Z0-9@:%_\+.~#?&//=]+)','\\1', $text);
-        $text=eregi_replace("(^|[ \n\r\t])(www\.([a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+)(/[^/ \n\r]*)*)",
+        $text=preg_replace('#(((f|ht){1}tp(s?)://)[-a-zA-Z0-9@:%_\+.~\#?&//=]+)#','\\1', $text);
+        $text=preg_replace("#(^|[ \n\r\t])(www\.([a-zA-Z0-9_-]+(\.[a-zA-Z0-9_-]+)+)(/[^/ \n\r]*)*)#",
                 '\\1\\2', $text);
-        $text=eregi_replace("(^|[ \n\r\t])([_\.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,4})",'\\1\\2', $text);
+        $text=preg_replace("#(^|[ \n\r\t])([_\.0-9a-z-]+@([0-9a-z][0-9a-z-]+\.)+[a-z]{2,4})#",'\\1\\2', $text);

         return $text;
     }

diff --git a/osticket/include/class.validator.php b/osticket/include/class.validator.php
index 284d7c7..697d99c 100644
--- a/osticket/include/class.validator.php
+++ b/osticket/include/class.validator.php
@@ -126,15 +126,15 @@ class Validator {

     /* Functione below can be called directly without class instance. Validator::func(var..); */
     function is_email($email) {
-        return eregi("^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$",trim($email));
+        return preg_match("#^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,4})$#",trim($email));
     }
     function is_phone($phone) {
-        $stripped=eregi_replace("(\(|\)|\-|\+)","",ereg_replace("([  ]+)","",$phone));
+        $stripped=preg_replace("#(\(|\)|\-|\+)","",preg_replace("/([  ]+)#/","",$phone));
         return (!is_numeric($stripped) || ((strlen($stripped)<7) || (strlen($stripped)>13)))?false:true;
     }

     function is_url($url) { //Thanks to 4ice for the fix.
-        $urlregex = "^(https?)\:\/\/";
+        $urlregex = "#^(https?)\:\/\/";
         // USER AND PASS (optional)
         $urlregex .= "([a-z0-9+!*(),;?&=\$_.-]+(\:[a-z0-9+!*(),;?&=\$_.-]+)?@)?";
         // HOSTNAME OR IP
@@ -149,9 +149,9 @@ class Validator {
         // GET Query (optional)
         $urlregex .= "(\?[a-z+&\$_.-][a-z0-9;:@/&%=+\$_.-]*)?";
         // ANCHOR (optional)
-        $urlregex .= "(#[a-z_.-][a-z0-9+\$_.-]*)?\$";
+        $urlregex .= "(\#[a-z_.-][a-z0-9+\$_.-]*)?\$#";

-        return eregi($urlregex, $url)?true:false;
+        return preg_match($urlregex, $url)?true:false;
     }

@@ -161,7 +161,7 @@ class Validator {
             return false;

         $ip=trim($ip);
-        if(ereg("^[0-9]{1,3}(.[0-9]{1,3}){3}$",$ip)) {
+        if(preg_match("#^[0-9]{1,3}(.[0-9]{1,3}){3}$#",$ip)) {
             foreach(explode(".", $ip) as $block)
                 if($block<0 || $block>255 )
                     return false;