From MTN website at
http://www.mtn.co.za/?pid=232088
Packet switched data usage will be billed as follows:
Packet switched data usage (data sent and received) will be billed per byte, per session.
A minimum of 1 byte per day will be billed, if a session was open but no data was transferred (from 00:00 to 23:59).
Where a session remains active over the 23:59:59 to 00:00:00 time period each day, a billable record will be generated as if the session was closed. The network will however keep the session active, and a new billable record will be generated for the same session, counting from 00:00:00.
Charges are rounded up to the nearest cent, per session i.e. a minimum charge of R0.01 applies to each new session.
In terms of the current regulatory regime in South Africa, please note that these tariffs and the MTN GPRS, GPRS+ and EDGE technologies may not be used to transfer or generate Voice over Internet Protocol (VoIP) traffic. Should it be found that VoIP traffic was carried over the MTN network using these tariffs or technologies, MTN reserves the right to cancel the agreement that you have with MTN, with immediate effect. You will also be charged retrospectively at R25.00 per Megabyte (VAT included) for any VoIP traffic transferred by such means.
No products or services, other than international packet switched data roaming, may be used or loaded on these price plans.
No price plans migrations are allowed into or out of these price plans.
Inclusive bundles do not carry over from month to month.
The inclusive data bundles and out-of-bundle tariffs only apply to on-net data usage. Data usage whilst roaming will be charge at the roaming networks data rate, as an additional cost.
