Exotel used to charge you only for SMS delivered to your customer. That is, only when we know that your customer has received the SMS on his handset. 

But it turns out that is not how the industry operates. Our gateway providers and their providers charge for delivering an SMS to a carrier's SMSC. That didn't make sense to us, so, we did not charge you. But in the last couple of months, our bills kept swelling and we didn't have much choice but to pass this over to you. 

So, From 8th August 2013, all SMSes delivered to the destination number's operator's SMSC will also be charged irrespective of whether the customer actually received it or not. We are told to believe that this is how the industry operates. 

Here is their rationale:
1. In India Operators only charge for originating SMS, there are no charges for SMS termination. Let's say a message is sent from Vodafone to a Reliance number. The SMS travels through Vodafone's network and waits to get delivered to Reliance's network (in the process completely utilizing Vodafone's network elements). So Vodafone says "You have used my network, now pay me!". 

2. Secondly when the message (SMS) is submitted for delivery to the end subscriber, the system re-tries many times (for over 24 hours) to deliver the SMS. So, the network utilization for the unsuccessful messages is actually more!

3. In most cases of non-delivery, the SMSs are not delivered due to following reasons: 
  a. The called party terminal equipment switched off. 
  b. The called party terminal equipment out of service area 
  c. The called party terminal equipment out of memory (not enough memory to receive the SMS). 
  d. Invalid number dialed by the calling party. 

So, operators make multiple valiant attempts to deliver your message and they charge us for it. 

You may find the following items in your reports because of this: