Source of version: 6
Exchange ActiveSync is extension of Exchange 2003 that allows a Pocket PC or Smartphone (2003, 2003 Second Edition or Windows Mobile 5.0 or Windows Mobile 6 device)synchronize with directly with an Exchange server (as opposed to the older PC based ActiveSync). Microsoft provides Exchange ActiveSync for free with Exchange 2003. For the special form called "DirectPush" the server needs to have Exchange Server 2003 SP2 installed.
The original implementation of Exchange ActiveSync requires the client to poll the server. On the mobile device you can specify the interval for this polling. Shorter intervals will put more strain on the battery of the device.
Unfortunately, with Windows Mobile 5, Microsoft have selected to make the polling the default setting of ActiveSync. As a result you may see your device wake up regularly without any real need. To avoid that you have to apply what is now known as the "Fake Server Hack". This is necessary because without a server set up you cannot change the sync schedule to "Manual". (You can remove the fake sever again after you changed the settings).
With Exchange 2003 Service Pack 2 and Windows Mobile 5.0 AKU2, Exchange is now able to push e-mail directly to the Windows Mobile device.
Technically this is solved through a long-time TCP request. The client (the mobile device) opens a request to the server but does not require an immediate response. The server responds only if anything has changed on the client's exchange datastore, or if the TCP request timeout has occurred. If the request times out the client sends another request, typically every 15 minutes. Sometimes network routers do not permit such a long TCP request life, and the interval is then automatically decreased at the cost of higher data traffic.
After the server notified the client that a change is pending the client initiates the ActiveSync connection. This is also done when the mobile device is in standby mode. Depending on your notification settings you can see through a blinking LED that new items have arrived. The ActiveSync client then issues another long-time TCP request. This is the reason why you will always see ActiveSync as an active program on the mobile device when Exchange ActiveSync is enabled.
Security: Special care should be exercised when establishing a DirectPush connection. If possible, use a SSL encrypted connection only. ''If you do not use an SSL encryption all data sent and received is not encrypted and may be captured by others without your knowledge.''
Smartphone 2002, Pocket PC 2002, Windows Mobile 2003, Windows Mobile 2003 Second Edition do not support this form of e-mail push. They may support the previous version that uses SMS messages rather than long-time TCP requests. Dataviz offers [http://www.dataviz.com/products/roadsync/winmobile/index.html|Roadsync] for Windows Mobile 2003 and Windows Mobile 2003 Second Edition Pocket PCs to use push e-mail with Exchange 2003 Service Pack 2.
Prior to Exchange 2003, Microsoft released Mobile Information Server for Exchange 2000. This was the first release of synchronization software for Exchange however it was not free. Microsoft no longer offers Mobile Information Server for Exchange 2000.
[http://www.pocketpcfaq.com/faqs/activesync/exchange_errors.php|Exchange ActiveSync Error Codes]
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