This may not be called hacking but I can define it as a trick,a trick with which you can use GPRS from Nepal Telecom for free.
Trick to use Service from Nepal Telecom
To you GPRS,you will need to activate GPRS on your SIM card and configure your cell phone to use GPRS on it and then you can use GPRS internet following the payment plan from NTC or by using free GPRS access from my idea.
This is such a simple idea.NTC usually deduct your money and charges you after you end GPRS session.You will be charged to use GPRS just after you end GPRS session.So to not to pay for using GPRS,just use GPRS as much as you can and when its time to disconnect,directly take out the battery from mobile phone before ending the GPRS connection and leave it for 10 minutes.
You can check afterwards and Find that your balance was not deducted.