I have tried to install sipwise 3.1 on a fresh debian installation and always get the following message:
  service apache2 restart
[ ok ] Restarting web server: apache2 ... waiting .
Setting up ngcp-ossbss-system (3.8.1) ...
Setting up ngcp-ossbss-xmldispatcher (3.8.1) ...
Errors were encountered while processing:
 ngcp-asterisk
 ngcp-reminder
 ngcp-services-ce
 ngcp-ngcp-ce
E: Sub-process /usr/bin/dpkg returned an error code (1)