The solution would be to have an analogue connection from end-to-end. But today, even analogue phones are connected to digital switching networks, so you can't even use ordinary landline phones and expect to get no delay. You can get "leased lines" from the phone companies that are analogue end-to-end, but leasing a tuned circuit that supports audio fidelity (ie. a 56 kHz leased line) will probably cost hundreds of dollars a month. Last time I saw an equalized analogue leased line was in 1980 when I worked at a radio station. It's possible analogue-only leased lines don't even exist any more. /cc @StrangeAttractor @LauraRitchie