This is no review, just an update.
The last few days I got switched by my ISP from ISDN to VoIP. As always I tried to solve this mostly on my own, my last job having been in IT-Helpdesk for Systematics/EDS/HP. And, as usual I checked not everything, and ended up Friday evening, the day of the switch, using a mobile XS Box Go to check the Status page of the order, and seeing, they switched to VoIP at 4 pm, so that should have happened (it being 6 pm). But while they send a couple of messages in the days before the switch announcing the order, and two to alert me to switch day, should I have missed reading the dead-wood-printed confirmation letter I received.
Turns out, my DSL-TAE-Adapter was the wrong one, but I found out, that the DSL-Port and Internet and VoIP would function without the Adapter, but with the Splitter, which was explicitly mentioned in the confirmation, that it should not be used. So I used it still, despite this information, to google for more information and found out that I should use a different colored Adapter (mine was blue, it was supposed to be grey) which would sometime be provided when buying the router (AVM 7390 in my case), sometimes not. If not, I could order it, and maybe get for free (I have not tried) from either AVM or my ISP. But I could open the Adapter and remove the wiring and put in a different place, so different pins from the DSL-Router-cabel where used, as I had nothing left to lose, I tried that. And it worked. The splitter is not used anymore, and I am happily online again with DSL. The configuration of VoIP was a breeze, I had done such things before, and it was also well documented. Finally I also removed my old ISDN-Telephone, which only use would not work anymore: to be able to call out or receive phone calls when power was down, the phone being powered by ISDN. As the phone would be connected to the router, when power is out, I would have no internet, no VoIP, nothing. Only probably my mobile phone would still be working for calls, but that is a different number. So I also removed my answer-machine and configured my router as a comfortable voicebox, taking calls and sending the soundfiles as mail (same goes for fax). Should have done that long ago, not being too fond with my answer-machine. Together with removing my ISDN-phone, I also removed a headset I bought used, to speak hands-free, but also never used much. That will be 3 devices connected to a power strip, I can remove for the cost of the router using a little more power (and getting warmer?), ISDN-NT, Answer-Machine and Headset.
So in the last few days I struggled to read, and since the death of Terry Pratchett (RIP) I am reading "Good Omens" again, bought for the Kindle.