Ravi Sir's Cards › AWS
SNS email vs SMS cost
What is a VPC: your own private network inside one AWS Region, example ThreeTierVpc 10.0.0.0/16.
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What this card says
Why do we need it?
SMS is billed per message and often starts in an SNS SMS sandbox. A class lab can burn money by accident.
What is it?
For learning the flow, subscribe your email to an SNS topic and keep SMS_MODE off. Production SMS needs spend limits and sandbox exit.
How to do it
Create topic → email subscription → confirm → TOPIC_ARN in env. Do not set SMS_MODE=1 unless you accept SMS charges.
TOPIC_ARN
Example
Ten students each request one OTP → ten emails, no SMS line on the bill.