/etc/init.d/isdn:409 contains the statement

| if [ -f /etc/ppp/options-$1 ]; then
|   options="$option `cat /etc/ppp/options-$1`"
| fi

There is missing an 's' after '$option' so ipppd will be called with the
extra-options from the cat'ed file only.

The correct statement should be

| if [ -f /etc/ppp/options-$1 ]; then
|   options="$options `cat /etc/ppp/options-$1`"
| fi