free calling card

Billing increments Each call is measured in basic units called billing increments.
Billing increments are occasionally called “per minute rounding.” Most billing increments
are one minute, although some cards will measure in two- or three-minute increments.
International calling cards may charge in six-minute billing increments, so if you
make a seven-minute call, your card will be rounded up to the next increment and
you will be charged for 12 minutes.

calling card
I bought a treo 600 in  January 2007 here in South Africa,of late the phone does not ring or vibrate for incoming calls.When I phone from another line ,you can hear that its ringing but the device is silent. Help me out LloydPost relates to: Treo 600 (GSM)