Telkom Mobile Query

All the offers I am seeing mention "Data available on Telkom Mobile network" as the small print to any offering. I am looking at the Note 3. It has 100 "all net" minutes, presumably meaning I can phone any network for 100 mins per month, and 5GB data with an asterisk referring to the clause mentioned.

Please can someone tells me what this means?

EDIT : To elaborate further, what is the difference between these two:

Telkom Mobile Internet Bundle 250 MB @ R38
All Networks Internet Bundle 250 MB @ R50