I am using a modern laptop or my iPhone to remote desktop into the old motherboard, connected to the RJ45 Ethernet and the RJ11 phone line.
Can I use the RJ11 to make landline calls?
FWIW, as it’s a salvaged motherboard, I don’t know the make and model. I was able to successfully run Windows 11 21996 on the motherboard. It works flawlessly, except for the fan control circuit.