I keep thinking this. If my gf is walking home I stay on the phone the whole way. Often I’ll walk towards her to meet along the way.

Or if I was walking along then waiting for a lift I might stay on the phone to them until I know they’re near?

Again, such speculation isn’t really helpful but it’s plausible. 21:28 to 21:30 is too close a time frame to be a pure coincidence (though if someone was following they may seize the moment if they can see the phone has been put down so this isn’t to pin the blame on anyone, just to say these 2 minutes are key).

You can’t vanish without a trace. You can’t! All their search energy is focused on the outdoors but these 2 minutes tell me either a car is involved or she went into a building. It’s one of those two scenarios.