Not the dialup chirping.

I once had two laptops on a bench side by side, different makes and models and different faults, nothing in common that might cause this. When I got them booted up to work on them, BOTH of them started making the same burbling XP noises I'd never encountered before.

This was back when Infrared was in use briefly as a data transfer method. Being slow and line of sight only it was soon made redundant by Bluetooth.

It turned out I'd accidentally aligned the IR ports just off center to each other and they were repeatedly failing and retrying to establish a link.