I'm not sure where you have in mind for adding filtering in the back end, but there is no such option in any case.
The closest thing is that when you edit a post type (at Toolset > Post Types) in the settings "Post Fields to be shown as columns in Post Type listing in WordPress Admin" you can specify custom fields to be added as columns when listing the custom posts. In the screenshot I've added a custom field Indexable to my Thing post type, and I can click to order the posts by that field, but there is nothing akin to filtering available.
I have added the fields as columns, but I would like to add filters for the "Call status" and "Origin" fields, filters of the same type as dates for example.
I have also seen that the search by custom fields cannot be activated for the telephone and email type fields. Is this correct?
Using Toolset - on admin Post listing page we only offer a feature that you can display the custom field. There is no native feature added using which you can search or filter on custom field columns.