Increase "hotline_delay" timeout to 30 seconds (for emergency calls)

[Someware]

Hello,
we use features.hotline_number and features.hotline_delay to place an automatic emergency call when a phone is hooked off. When a disabled person is unable to press keys but hooks off the ohine a emergency hotline is called.

But for this usage the maximum delay of 10 seconds is too short. With 10 seconds we get too many false emergency calls. We need to set this value to 30 seconds. How to do this? For us it does not make sense to limit this value to a maxium of 10 seconds.

Is there any other possibility to place an automatic call to a specified number after 30 seconds when the phone is hooked off?

I tried to to it with an XML app and Action URL but this seems to be a but that seems to be a difficult and unstable solution.
Regards, Tobias.