On a single CPU in an ATX case, yes, definitely, with power to spare. Possible on a modern Raspberry Pi too, if you hooked up USB modems that FIFO buffered on t

On a single CPU in an ATX case, yes, definitely, with power to spare. Possible on a modern Raspberry Pi too, if you hooked up USB modems that FIFO buffered on the modem itself, used something like an Arris multiline modem that will connect over Ethernet, or alternatively, could figure out a way to attach a 200+ multiline PCI modem card to your Pi. Though you'd need to talk to your telco if using an Arris as they used this weird parallel connector that I don't recall the name of.