1) Postpaid connection with at least 2500 security deposit.
2) A Blackberry device running BB OS 7, for example: Bold 9900, Curve 9360, etc
3) Go home with your postpaid SIM and call 120 (Blackberry helpline), ask them to convert your package to BIS. They will obviously ask questions about NIC number and whatnot, proceed with that and get your package converted.
4) Enjoy unlimited data.
Credits @inception
Sent from my Nexus 6P