of all data (both email and MDS traffic) that travels between the BlackBerry phone and a BlackBerry Enterprise Server. Most providers offer flat monthly pricing via special Blackberry tariffs for unlimited data between BlackBerry units and BES. In addition to receiving email, organizations can make intranets or custom internal applications with unmetered traffic. With more recent versions of the BlackBerry platform, the MDS is no longer a requirement for wireless data access. Starting with OS 3.8 or 4.0, BlackBerry phones can access the Internet (i.e. TCP/IP access) without an MDS – formerly only email and WAP access was possible without a BES/MDS. The BES/MDS is still required for secure email, data access, and applications that require WAP from carriers that do not allow WAP access. The primary alternative to using BlackBerry Enterprise Server is to use the BlackBerry Internet Service (BIS). BlackBerry Internet Service is available in 91 countries internationally. BlackBerry Internet Service was developed primarily for the average consumer rather than for the business consumer. The service allows users to access POP3, IMAP, and Outlook Web App (not via Exchange ActiveSync) email accounts without connecting through a BlackBerry Enterprise Server (BES). BlackBerry Internet Service allows up to 10 email accounts to be accessed, including proprietary as well as public email accounts (such as Gmail, Outlook, Yahoo and AOL). BlackBerry Internet Service also supports the push capabilities of various other BlackBerry Applications. Various applications developed by RIM for BlackBerry utilise the push capabilities of BIS, such as the Instant Messaging clients (like Google Talk, Windows Live Messenger and Yahoo Messenger). The MMS, PIN, interactive gaming, mapping and trading applications require data plans like BIS (not just Wi-Fi) for use. The service is usually provisioned through a mobile phone service provider, though BlackBerry actually runs the service. BlackBerry PIN The BlackBerry PIN (Personal Identification Number) is an eight-character hexadecimal identification number assigned to each BlackBerry device. PINs cannot be changed manually on the device (though BlackBerry technicians are able to reset or update a PIN server-side), and are locked to each specific BlackBerry. BlackBerry devices can message each other using the PIN directly or by using the BlackBerry Messenger application. BlackBerry PINs are tracked by BlackBerry Enterprise Servers and the BlackBerry Internet Service and are used to direct messages to a BlackBerry device. Emails and any other messages, such as those from the BlackBerry Push Service, are typically directed to a