You pay for each SMS which you send via Muzztech Bulk SMS software or via Bulk SMS API. In Muzztech you can start sending SMS from INR 0.13 to INR 0.20 per SMS. and if your SMS volume requirement is high, then you can send per SMS in ₹0.13 (which is lowest in SMS industry). Muzztech Bulk SMS Service is free to test - Free credit will be provided after signup.