Hi, Mario.
I'm not sure where I found it in Admin->Sysconfig....
Here is the line to put into Config.pm
$Self->{'Ticket::Frontend::NeedAccountedTime'} = '1';
It will give you manadatory accounted time on new tickets and any other articles your agents try to post. The only exception I found is bulk action. This form will not ask for accounted time.
I have OTRS::ITSM. Ticket type is mandatory for my agents in phone tickets. I believe it's by default in ITSM as I don't remember I did anything to achieve that.
I hope this helps.
Regards,
Anton.