How do I know whether the bill is already paid?

Use the option Quick Pay and supply the Telephone number with STD code, it will display the message "bill is already paid' if paid up already.

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How do I receive a bill for the payment?
After successful payment, you will receive an SMS notification of the payment from BSNL with a link to download the bill.
Money is deducted from the bank account, didn't receive the SMS confirmation or bill?
If money is deducted from the bank account and not updated in your BSNL account, we recommend you to wait for 24 to 48 hours. Support team will provide the response and resolution.
I have made the payment and it failed. Can I make the payment again?
Yes. Mobile app will display a warning if there is a payment already attempted. We suggest you to wait for 15 minutes and if there are no successful transactions, you may can re-attempt the transaction.

BSNL EPAY Helpdesk