Just made a mobile to another mobile from Australia to UK and was amazed by how clear and non laggy it was. How does the signal get sent back and forth from one side of the world to the other? Satellite or cable? Radio or fibre optic?
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Calls will go via fibre-optic cables.
For several decades now, they’ve been transmitted all-digitally, so there won’t be any quality degradation.
Earth radius is 6378km. Halfway around the earth’s surface is pi*r, so 20,000 km
Speed of light in air is 3×10^(8) m/s, or 300,000 km/s, but in fibre optic is about 2/3 the speed of light in air/vacuum, so around 200,000 km/s.
Therefore it’ll take the light one tenth of a second to go halfway around the world.
The perceived delay is the round-trip time, so two-tenths of a second (1/5th second). This is the fastest it could possibly be. In reality the route will not be the shortest possible, and there might be a few other routing delays along the way.
This delay is fairly imperceptible, and probably shorter than coding/decoding delays that you get in any mobile call, even between two people standing next to each other.
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