Use systemd restart

src/freedombone-addsipuser

@@ -155,6 +155,6 @@ else
     echo "SIP user $MY_USERNAME added"
 fi
 
-service sipwitch restart
+systemctl restart sipwitch
 
 exit 0

src/freedombone-rmsipuser

@@ -99,7 +99,7 @@ fi
 
 remove_sip_user
 
-service sipwitch restart
+systemctl restart sipwitch
 
 echo "SIP user $MY_USERNAME removed"
 exit 0