You have installed the German language files (prompts) of the city of Pforzheim on your Asterisk system. The menu of your answering machine is German. But if you have only one message, the menu always will break off after the announcement of „Sie haben“.
Asterisk wants to open the file
1F.gsm for the voice of 1 – „eine“. This file is missing.
The missing file exists under a different name, namely as
eine.gsm. If you rename the file or even better create a symlink, it will work:
root@linux# cd /var/lib/asterisk/sounds/de/digits root@linux# ln -s eine.gsm 1F.gsm