How am I charged for my IDD usage (ZONE GlobalDial Plus)?

ZONE Telecom > Business > ZONE GlobalDial Plus Service
Registration Fee / Administration Fee
Monthly Subscription Fee
$8.00 per access number (subject to GST)
Call-Me-Back Charges 
for calling back to Singapore
40 cents per minute 
Call-Me-Back Charges 
for calling to overseas destination
20 cents per minute (callback service) + ZONE GlobalDial IDD rates (overseas IDD usage)
•    The incoming roaming call will be charged by your mobile operator.
•    This service is not recommended for calls to Malaysia and our DialForward service.