Before we begin, make sure the phone has a data plan activated and that you can browse the internet using Internet Explorer on the phone.

If your Microsoft Exchange 2003 Server is using Forms Based Authentication, and you are using SSL with the forms based (You SHOULD WHY ARE YOU NOT USING SSL!!!?) then you will need to either get a certificate from a 3rd party that is trusted by the device, or you will need to transfer the certificate authority's root certificate to the phone and intregrate it with the Windows OS on the phone.

Because we are cheap, we are going to use our own certificate and save ~$60.00 a month.

You will need to use Internet Explorer and web browse to your Certificate Server on your network. Usually it will be something like, http://adserver/certsrv replace http with https if you use SSL on that server (You should be anyway.) and replace adserver with the name of the server running IIS and Certificate Services.

At the bottom of the webpage, click on Download a CA certificate, certificate chain, or CRL. After the next page loads, click on Download CA certificate at the bottom. You will be presented with a file download dialog, save the file where you can find it later.

Close Internet Explorer and then plugin the MDA Phone into your computer with the USB cable. Make sure you have ActiveSync installed from Microsoft. Navigate to the My Computer, and you should have a new device called 'Mobile Device' or something similar. Nice big orange thing.

Copy the certificate into that device, under the My Documents folder on the device. Then on the device itself, use the File Explorer to find the certificate file, and click on it and choose Yes to import the certificate.

Now you can proceed to setting up ActiveSync on the phone device itself to connect to your Microsoft Exchange 2003 server.