• Rule 2. If you are wanting a new phone or other free gift, shop around for the lowest priced monthly deal and toss the sim card in the bin.

The networks offer such aggressive retail deals, and rely on the user to pay the substantial premiums on usage of peak and per minute billed airtime to recoup the profits. They lose out to those astute users who throw away the sim card but use the new phone and free gift.
Look for the best valued airtime deal - lowest per second rates and peak rates to all networks.

The cost of a minute

The average call is about 50 seconds in South Africa - made up of a few long calls and many short ones. So the average loss is much greater than 10 secs. "I'm leaving....I'm waiting...I'll be there just now...etc"

Rule 1. Per second packages are almost always much better value.

If you are paying per minute (or the first minute) then multiply the published rate by 1.7
e.g. a 240 minutes package charges R2.35 peak. So the effective rate is about R4.00 a minute if you worked it out on average seconds used.
Or another way to look at it is that if you added up all the seconds used in the 240, you'd average out at about 145 minutes. And the monthly charge of R430 means you are really paying about R3 for the average included minute. If you chose a package that charged you about R1.90 per minute on a per second basis, your spend would be R275, which means you are paying R155 per month for the free phone (R3720 over 24 months). And that's assuming you don't pay more than your monthly R430.