sipdate inserts date stamps into SIP packets sent from germany’s popular router Fritz!Box to attached IP phones. This is needed for certain Cisco models in order to be able to use the newest firmware.
See [1] for more details and network configuration. libnetfilter_queue git version needs to be installed and an iptables rule set.
make_sipdate.sh fetches, copies and patches needed files from libnetfilter_queue, builds and installs binary and systemd service.
[1] https://www.ip-phone-forum.de/threads/korrekte-uhrzeit-auf-cisco-8961-9951-9971-an-fritzbox.289093