This is how much cheaper it is to call via Whatsapp in SA

Making a three-minute call over WhatsApp instead of cellular can save you as much as R3, depending on which service provider you use.
But the quality of WhatsApp calls are heavily dependent on network strength.
An average WhatsApp call uses anything from 0.15 MB to 0.47 Mb per minute, a Quora forum found.
Comparatively, a cellular calls cost R1.23 per minute at Vodacom, 99c at MTN, 66c at CellC and 70c at Telkom. Apart from Vodacom, these rates are the same for pay-as-you-go and contract clients.
You’d save a substantial R3.48 calling on WhatsApp at Vodacom, rather than cellular. The mobile company has one of the highest cellular call rates, a price comparison by Business Insider South Africa found.
The cost difference between a Whatsapp and cellular call is the smallest at Cell C, while data packages at Telkom were consistently the cheapest.
Business Insider South Africa compared the price of a three-minute WhatsApp call with cellular calls at the country’s four biggest cellular providers.
Read more: https://www.businessinsider.co.za/its-r3-cheaper-to-make-a-3-minute-call-on-whatsapp-compared-to-cellular-depending-on-your-provider-2018-5