A technical question here - not important but it's been puzzling me for years.

Why is it that whenever you make a mobile call, there is signal disruption whilst you hear the ring tone. It almost always happens (and has done on every phone I've used over the last twenty years), often being worse for the first two or three rings.

Since it's a digital signal I cannot understand how this distortion happens; usually the subsequent call is faultless.

There are two typical types of change to the sound: firstly something that sounds rather like a loose connection, and secondly a sound as if you are listening to the ring tone underwater.

Does anyone have any idea how and why a digital signal can suffer in this way, and why it seems to be so common listening to the ring tone even when the rest of the call has immaculate quality?