Hello world.
In a recent video of Windows 11 I noticed Dialer is still a thing in Windows 10. As my internet still runs on VDSL2, because I am in Germany, I have few telephone numbers associated. I would want to use these on my PC. I currently use the WiFi, as it would be quite a hassle setting cables but I can if needed.
How would I go about setting up Dialer?
My router supports Telephones.
Alvast bedankt.
Windows Dialer is for modems. You’ll need a direct connected modem to use it.
Okay, I’ll get a modem and phone cable. Now I need a USB or pci extension card to support the RJ11.
You probably don’t want an ISDN modem, and that Windows dialer is pretty useless for you.
However you most likely have an ISP that just uses SIP over a separate IP network(Voice-over-IP, VoIP).
AFAIK German providers are forced by law to give you the SIP credentials(as part of the “routerfreiheit”), and you could just install a SIP client on your computer and use that. (SIP basically is telephony over network)
Keep in mind that probably only the ISP-provided cable modem can make use of the separate, guranteed-bandwidth VoIP Internal network.
This usually isn’t a problem, unless your connection is heavily loaded or unreliable.
Sometimes the ISP-provided modems support some kind of SIP relay. I assume they using it will still make use of the separate network.
GrĂĽĂźe aus NRW 
I have the Telekom Speedport Smart 4 or something. I could hook up a rotary telephone to it and it might work.
Do you have any SIP in mind?
dialer is still supported for backward compatibility and disasters. its just legacy support in case the world ends… (for reals).
the idea is that dialer will be able to use any phone line not just a dedicated internet pipe. so should allow networking to resist a catastrophic attack or natural disaster that takes the WWW down.
I’m fairly certain the Windows Dialer just sends AT commands to a serial modem. It’s just some dumb leftover.
It’s not a modem in itself, although software-based modems do exists(e.g. minimodem). You could use those over a soundcard, connected(via wires or acoustic couplers) to a phone line(although I suspect actual phone lines still need to be connected via a Telephone exchange, a rare occasion in any sort of apocalypse).