Amazon Cognito isn't delivering SMS text messages to my app's users

Question

I have created a AWS Cognito user pool where user can login using

• Email
• Mobile number

I am verifying only "phone number" in attributes so all verification and forget messages going via mobile text SMS and It was working find few days and suddenly stopped sending messages.

Note :

• https://aws.amazon.com/premiumsupport/knowledge-center/cognito-troubleshoot-mfa-sms-delivery/
• My Amazon SNS limit is 100 $ and only 2$ is used .
• Graph shows only 2$ used
• I am able to send text SMS using SNS console
• No issue found in cloud watch matrix in cognoto and SNS
• https://github.com/aws-amplify/amplify-js/issues/6344

Updated : I have created new region in Mumbai region and no SMS sent but when i have created in N Verginia SMS sent by pool.

Any information or advice greatly appreciated 

Answer 1

So after spending many hrs. to debug issue found Major "BUG" into AWS Cognito Let me explain Step by Step

1. I have created an AWS Cognito pool in the Mumbai region Asia Pacific (Mumbai) ap-south-1  which uses SNS text messages to send OTP messages.

2. Requested Mumbai region SNS to increase Limit to 100 USD 

Everything was working fine for a few days and suddenly all SMS text messages stopped.

Debug Steps :

1. Uses following link and no issue found in 100 $ limit only 2 $ is used.

• https://aws.amazon.com/premiumsupport/knowledge-center/cognito-troubleshoot-mfa-sms-delivery/

2. I have created a new Cognito pool with the same configuration into the same  Mumbai region and try to send message no message sent by AWS Cognito pool.   

 3) I have created a new Cognito pool with the same configuration into the different  N Verginia region and try to send messages ,messages sent without issue.

4. I have used the Mumbai region SNS and found no issue in the message.

So where is the issue ?

BUG :  

• https://github.com/aws-amplify/amplify-js/issues/6344

In my case AWS Cognito internally uses Singapore region to send SMS text messages and where my Limit is 1$ since I am using Mumbai region Cognito should use Mumbai region not Singapore region.

Unfortunately, there is no public documentation available for users to know which is the closest region to the one they have selected. Upon sending SMS text messages. After raising request for all Asia Pacific  region issue is resolved .

• https://forums.aws.amazon.com/message.jspa?messageID=957242#957242

Sad part after raising question in AWS forum no help received from AWS, they > are looking to buy support , since nothing explain in Doc and this is AWS bug should be documented and support by AWS.

Customers are losing business just because of AWS fault.

Answer 2

Your Cognito verification sms are sent from different region than your infrastructure region. That's the key to resolve the problem. For example: My Frankfurt Cognito Service sends verification sms from Irland Region. You could check this via Simple Notification Service (Mobile text messaging - Succes / Failure ratio). That's the magic behind AWS and Cognito.