Interesting statistics about mobile phone usage:
In the UK, the number of outgoing voice calls made to the number of text messages is 0.6:1; in South Africa as a whole the the ratio is 3:1 for pre-pay phones; and in rural communities the average ratio is 13:1. Text messages are cheaper than phone calls, so this data, looked at from a western perspective, seems surprising. However, when considered in the context of a community where a significant number of people are illiterate it is more understandable.
from a talk given by Arun Sarin, Vodafone Group Chief Executive, last February.