Found the gen Z kid lol.

Anyone who actually used it was painfully aware of that fact. If anyone wanted to make a phone call, no more internet for you, and in some cases incoming phone calls could bounce you offline. Some people paid for a dedicated phone line for the internet but that was extremely rare for personal use.

This pic is an acoustic coupler, which played sounds and listened to them from the handset. Modems would connect directly to the phone circuit, bypassing actual sound waves (although they did still have a little speaker so the you could hear what they received).