After you have used up the 250 GB, the speed will be slowed down to 256 kbps/256 kbps. If you want to continue with the same speed, you can purchase a data pack at 10 GB for $10, 20 GB for $15, 50 GB for $30, 100 GB for $50 and 200 GB for $80. The data from the data pack will not be carried forward into the next month.
You need a handset to use the netphone. The charges are on pay-as-you-go basis. if the modem you have is not VoIP enabled, you can purchase a VoIP adapter. Local calls and standard national calls on the netphone are untimed and charged at 15c. Calls to Australian mobile are charged at 29c per minute.