Hi guys,
it seems as if my description has not been exact enough: nearly all mobile phones support to configure by the user the possibility of an ascending ring tone (not the iPhone obviously). Here is a more exact description: if the ring tone has a duration of 20 seconds, it will raise the volume by one step when starting with the 2nd cycle of the ring and so on till it reaches maximum volume.
This is a interesting functionality and cannot be compared with trying somehow to emulate within the limitation of the maximum duration of a iPhone ring tone (30 second).
It should be also very easy to implement so I wonder if this could be provided by the next version of iOS delivering really an added value.