Connecting two dial-up modems using a VoIP ATA
Or you can emulate the POTS network: two wires with 24-48VDC present.<p><a href="https:&#x2F;&#x2F;www.epanorama.net&#x2F;circuits&#x2F;teleinterface.html" rel="nofollow noreferrer">https:&#x2F;&#x2F;www.epanorama.net&#x2F;circuits&#x2F;teleinterface.html</a>