AWS SNS

AWS SNS (Simple Notification Service) can send SMS as one of its message types. If your stack is already on AWS, it's the cheapest and most-integrated option.

Pricing

• Free tier — 100 SMS/month for the first 12 months.
• US SMS — from $0.00645 per message (Transactional category).
• International — varies by country; pricing is published at https://aws.amazon.com/sns/sms-pricing.
• Promotional vs Transactional — two SNS categories; Transactional has higher deliverability for OTPs but both are available.

Setup

1. In the AWS SNS console, open Text messaging (SMS) → Preferences.
2. Set the default message type (Transactional recommended for OTPs).
3. Optionally, request a spending quota increase — SNS defaults to $1/month for new accounts.
4. For some countries (US, Canada, India), you'll need to register a sender ID or 10DLC campaign. SNS walks you through this in the console.
5. Create an IAM user with sns:Publish permission.

import "github.com/gopackx/go-notification/channel/sms/sns"

notifier.RegisterChannel("sms", sns.New(sns.Config{
    Region:          "us-east-1",
    AccessKeyID:     os.Getenv("AWS_ACCESS_KEY_ID"),
    SecretAccessKey: os.Getenv("AWS_SECRET_ACCESS_KEY"),
    MessageType:     "Transactional",
    SenderID:        "YourBrand", // where supported
}))

Configuration reference

When SNS is the right pick

• Your app already runs on AWS (Lambda, EC2, ECS).
• You want CloudWatch metrics on SMS delivery out of the box.
• You need only a single SMS provider and care more about cost than multi-region redundancy.

When to use something else

• You need specific country coverage Twilio or Vonage support better — AWS SNS has gaps in some APAC and African markets.
• You need OTP primitives — AWS has Cognito or Pinpoint; Twilio has Verify. This library's SMS driver is the low-level message primitive only.

Troubleshooting

• Hitting the $1/month cap — request an increase via Support; they usually approve quickly for a legitimate transactional use case.
• Message never delivered, no error — SNS quietly drops Promotional messages in some countries. Switch to Transactional.
• Sender ID ignored — not supported in the destination country; SNS falls back to a random short code.