Optimizes idle time disconnects depending on the charging information received during the connection. This value specifies the minimum inactivity time (channel is silent) in percents of the current charging interval length and is only used for outgoing connections. Incoming connections are disconnected after idle time according to the value biboPPPShortHold. Please note that this only works if your ISDN port has the AOCD service enabled (advice of charging during the call). For instance in Germany this is an extra paid service. (Even the 'Komfortanschluss' does only include AOCE [advice of charge at the end of the call], so AOCD has to be ordered and paid extra.)