[h2odragon]

Actual circuit switched connections, regular voice calls, would've been quite low latency. Later there got to be some delays from digitization; even then it would've been hard to detect in actual conversations.

ISDN lines were favored by radio stations forever because of the reliably low latency and jitter they offered.

Actual numbers? I wanna guess ~100ms max for a cross country call, pre-digital long distance. Maybe 350ms post digital. IIRC the ISDN hop I had to a local CO was ludicrously low, like 9ms? but i could be wrong. That was years ago.

Digital links for internet connections were lower inherent latency but then had layers of other modulation happening on top of them, and the variations there are a different order of thing. I assume you mean bare link latency.

I've NFI how many different layers of re-encoding your data might be expected to go through on a standard call today; but the list of transitions would probably be long and amusing.

[wmf]

I had ISDN in 1996 and my ping to a server in the same city was something like 8 ms. ISDN probably contributed 1 ms each way. The simple Web pages of the time loaded so fast.