Send *124*4#  

Steps 

Open 3G Modem Application. 
-> VISIONTEK 82GH 3G Modem Application 
->  Click ON USSD
-> Type in Enter USSD Number : *124*4# 
-> Click on Send 

U will get the details. 

16:00:13
[Sent] *124*4# 
16:00:13
[Received] GPRS 24Hr Acc bal 4540.39MB and valid upto 18.11.2011. GPRS Night Acc has expired.