I have an O2 XDA IIs which I wanted to sync over GPRS with my Exchange server in the office. Activesync used to work smoothly when I used to put the phone in the cradle but it failed to sync whenever I tried to sync it over GPRS or Wi-Fi connection.

I found that the problem was with communication over SSL (Secure Socket Layer) because the Exchange virtual directory in Microsoft Internet Information Server (IIS) is configured to accept only Secure Sockets Layer (SSL) connections on our server. Naturally this has been done to keep the security in place and to ensure that no passwords are sent out in clear text since Basic Authentication is enabled and Integrated Authentication is turned off.

Upon further research I found that Microsoft-Server-ActiveSync and Outlook Mobile Access virtual directories only try to connect with the Exchange virtual directory over TCP port 80 (HTTP) and does not make use of TCP port 443 (HTTPS).

I also tried adding Root Certificate to the PDA using the Microsoft solution as highlighted in their KB — but things do not work so easily for me — ANYTIME. It’s always hard work.

The best option was to take off SSL for OMA and ActiveSync. I exported the configuration of Exchange directory from IIS and imported the same under ActiveSyncPDA. After the import I removed SSL option from the virtual directory. The next step was to add a new parameter in the registry:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesMasSyncParameters

and set it to point to the new virtual directory called ActivesyncPDA.

Restarted IIS and this time the sync from PDA worked over GPRS and Wi-Fi connections.