 Windows Mobile 2003 , originally codenamed " Ozone " , was released on June 23 , 2003 , and was the first release under the Windows Mobile banner . It came in four editions : " Windows Mobile 2003 for Pocket PC Premium Edition " , " Windows Mobile 2003 for Pocket PC Professional Edition " , " Windows Mobile 2003 for Smartphone " and " Windows Mobile 2003 for Pocket PC Phone Edition " . The last was designed especially for Pocket PCs which include phone functionalities . The Professional Edition was used in Pocket PC budget models . It lacked a number of features that were in the Premium Edition , such as a client for L2TP / IPsec VPNs . Windows Mobile 2003 was powered by Windows CE 4 @.@ 20 . 
