So it means you have received a CoinDcx voucher FROM Paytm for using Paytm to pay your bills! If yes, it's all fine! But remember, you will have to do full KYC before you can redeem the voucher. So if you are ready to do full Kyc, then go ahead!

I use CRED for my credit card bill payments and I had earlier received a voucher worth 200 rupees for Coinswitch. I have never used it because I never wanted to do KYC for such miniscule amount of bitcoin. These are just promotional techniques so you should not face any issue. But again, a full KYC will be needed before you can redeem such vouchers. So think about it before you actually redeem this voucher.