A number of customers have been reporting issues with SMS interception on the T-Mobile Dash handset. On these devices the SMS interception does not work through either the Microsoft or In The Hand class libraries. This is specific to the T-Mobile ROM as other branded versions of the same device, such as the HTC S620, do not have the problem. The culprit is a badly behaved IMessageFilter implementation which stops the standard interceptor from working. You can fix this issue by removing the entry from the registry. Take a look at this registry key:-
In here you’ll find 2 entries by default on Windows Mobile 5.0:-
If you find additional entries here try deleting them (make a backup first so that you can restore if necessary) then reset the phone. This should allow the normal SMS interception mechanism to work again.
On Windows Mobile 6 the above registry key is not present by default, therefore the standard SMS interception will work without any additional rules registered.