Modify Read() waiting time for user input

When a user is asked for entering some PIN (for example in Conference Room), there is a predefined waiting time before something else happens.

For example, the autogenerated line:
exten => 3707,n,Read(PIN,enter-conf-pin-number,)

Is there a possibility to change that predefined timeout parameter of the Read() function in the ConfRoom, for example to this:
exten => 3707,n,Read(PIN,enter-conf-pin-number,20)

As I could see, this is probably not possible since it is hardcoded somewhere, but I would like to know the file where it is hardcoded to change this to some other value?

I am aware that it will be changed during the next update, but nevertheless I would like to play with it.

It would be interesting to have option to select read() timeout withing the Conference module.

Many thanks for information provided!