Do I need to setup chain of telemarketers in AWS SNS to send SMS?

Yes, you do need to set up a chain of telemarketers to send SMS messages to India using AWS SNS. This is a requirement set by the Telecom Regulatory Authority of India (TRAI), not by AWS itself.

To send SMS messages to India, you need to follow these steps:

1. Register your company and use case with the TRAI through a Distributed Ledger Technology (DLT) portal.
2. Create the required Telemarketer chains.
3. Register your sender ID in AWS End User Messaging SMS.
4. Specify the Entity ID and Template ID values when sending messages.

Regarding your specific questions:

1. You don't need to register with all telemarketers. You should create a chain with at least one telemarketer. This is done through the DLT platform where you registered your company.

2. AWS SNS requires the chain of telemarketers because it's a regulatory requirement in India, not an AWS-specific requirement. You won't be charged twice for sending SMS messages. The telemarketer chain is part of the regulatory process, not an additional service provider. You'll still be billed by AWS for the SMS messages you send through SNS.

The process might seem complex, but it's designed to comply with India's regulations for SMS messaging. The chain of telemarketers helps in maintaining transparency and accountability in the SMS ecosystem as required by TRAI.

Remember that there may be fees associated with registering your company with the DLT provider, but this is separate from the charges for sending SMS messages through AWS SNS.
Sources
India sender ID registration process in AWS End User Messaging SMS - AWS End User Messaging SMS
Register your company and use case with the TRAI and create the required Telemarketer chains - AWS End User Messaging SMS