As a prepaid subscriber, now you can reload your credit via SMS. This service is free of charge.
How to access SMS Credit Reload

  Step 1
Type Refill<space>14 digits reload voucher code, send it to 999
One thing that you have to remember, voucher code must be typed with no space, if you type incorrectly, system will reject the transaction.

  Step 2
If you succeed, you will get the reply immediately.

  You will get this notification, if you typed the voucher code incorrectly
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