system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do internet-based voice calls have lag but standard phone calls don't?

I've got some family in Australia and it's always amazed me how a WhatsApp call, despite both having very fast internet speeds, will have a bit of lag (normally around a second or two) but a standard landline phone call the same distance will have none at all. And the same even applies to local calls. 

Essentially, what is it about standard phone communication (landline or mobile) which allows it to transfer data thousands of miles absolutely instantaneously? Will we ever hit internet speeds which allow the same thing?
gpt
Standard lines don’t really transmit data as much as transmitting signals. 

Voice over IP works by sending data in packets over the internet. Internet protocols work differently than standard phone lines. Standard phone line calls basically happen at the speed of electricity. VOIP data is sent in packets that get routed through the internet along with all other kinds of data. The time it takes for this processing is called latency. When your device sends of the stream of voice data in these packets it doesn’t care how they get there and they may take different routes and arrive out of order and have to be out back together, that’s called jitter. Together, latency and jitter are what you experience as lag. There’s also another concept called buffering, which basically is a way to compensate for the time all the above takes. All of this happens and rehappens throughout the call and is constantly changing. Both clients basically measure the time it takes to send and receive packets and try to compensate.