Verizon is a dividend-paying machine.Verizon (VZ 0.81%) has one of the highest dividend yields in the S&P 500 at over 6.5%. That puts it several times above the index's level of 1.3%. The concern is that a high dividend yield often signals that the payout is at a higher risk of reduction. However, that's not the case for the telecom stock's dividend. It's on an increasingly sustainable foundation, which has been on full display this year. Here's a look at the factors driving this view.Improving where it mat ...