It's all goes digital at some point, but not VOIP. McMurdo Station, population 1000, has old analog phones or the crappy beige variety. There's several hundred of them (400 maybe) with a Microwave uplink to Black Island, 22 miles North of McMurdo. From Black Island the signal is uplinked via the NPOESS satellite system to Centennial Colorado, where it's dropped on the public phone system. No VOIP anywhere in there. The South Pole station, however is VOIP fed by several ancient satellites that peak low enough to be seen at the bottom of the earth.