When you’ve got a new call on the internal answering machine of the Fritzbox 7490, the Info LED starts to blink. (It can also blink because of other reasons, which are not the topic here.)
To stop the blinking, you should listen to the call. But the blinking does not stop when you listen to the call from the Anrufe/Calls page, see first screenshot below.
No, you need to listen to the call from the Anrufbeantworter/Answering machine page to stop the Info LED from blinking. See 2nd screenshot.