1 second of delay jitter with random dropouts and echoes are typically caused by problems at the ends (poor wifi/cellular signal, too much load on cpu during a

1 second of delay jitter with random dropouts and echoes are typically caused by problems at the ends (poor wifi/cellular signal, too much load on cpu during a high res video call, laptop overheating, etc). UDP protocol allows to make a call even in the presence of such issues, whereas circuit switching with reliable clocking would simply not work at all.