How to access all activities by RESTful API?

Hi all,

When calling this request 'GET   /data/activities/contact/{id}?startDate={startDate}&endDate={endDate}&type={type}&count={count}', I tried to ignore the parameter 'type', and it failed to get any activity data.

When accessing activities through RESTfull API, is the parameter 'type' necessary?

Is there any way to get activities of all kinds of types?

BTW, is there any way to get activities of  all contacts?

Thanks,

Biao