Amplify-js: Auth - SignUp SMS Verification Code not getting sent/delivered.

[AakashPat]

Describe the bug
Upon signing up with a phone number, the Verification SMS with the 6 digit code is never sent to the phone number. After trying to resend the code multiple times, the message is never received.

To Reproduce
Steps to reproduce the behavior:

1. SignUp using phone number
2. SMS not received.
3. Resend verification code.
4. No SMS received

Expected behavior
A SMS Verification code is sent to the phone number used during SignUp.

Additional context
I have already raised a Service Quota Increase ticket and have that increased. I have also explicitly set the spending limit on the SNS (Text Messaging) Console.
I have tried using the Cognito Hosted UI to Sign Up and am facing the exact same issue with that. The verification SMS is never received.

My SNS service is working as expected as I can send out other SMS communication to our users using the aws-sdk.

Also, if the user registers using the email address, an email is promtly sent to the user with the verification code. Only SMS are not delivered.

[shreyansjain]

+1 to this issue.

We have recently started experiencing the same issue (Spending Limit/Service Quota issues have already been resolved).
Wanted to highlight few observations:

• Started happening start of this week (week of July 12th)
• Sending Transaction messages via AWS console works to the recipient of the OTP/MFA user
• Mostly happening this to users/phone numbers in India (Users with Canadian cell number didn't have this issue)

I have asked AWS team to confirm if it was related to recent changes due to ILDO

[AakashPat]

@shreyansjain
Similar situation at my end.

• 14 July is the first time I faced this issue.
• Sending Transaction messages via AWS SNS Console works for me too.
• My AWS Cognito Pool is based in Frankfurt (eu-central-1). During assessment, I created User Pools in other regions (_us-east-1_ and _ap-south-1_) and those User Pools are able to send verification messages just fine. Only the _eu-central-1_ pool is unable to send messages. (Also tried with a second and a third User Pool created in the same region; Still unable to send messages through Cognito).
• In my case, the User Pool is unable to send messages to any phone number whatsoever. I have tried with _US, DE, BE_ phone numbers. None are receiving any SMS Verification Code whatsoever.

In order to get a faster resolution to avoid impact on business, I am seeking approval for getting a Support Plan from AWS. It will cost us 29$/month. All this for something that should be very straight forward in the first place.

[shreyansjain]

That's strange, UserPool in ap-south-1 is the failing for me to send to IN numbers (CA/US numbers are getting delivered).

The worst case is, this the first point of entry to our platform and if users are not able to receive verification codes, they won't be able to use the platform.

I'll update once I hear back from them and/or please do the same.

[AakashPat]

@shreyansjain , I can understand. Same is the problem we're facing. If users can't even register, it will impact business very heavily. For now, I have paid for Developer support and have raised a ticket with AWS. I am awaiting a response from them. Will update this thread once I hear from AWS Support.

[shreyansjain]

Heard back from AWS PM:

I’ve reviewed the AWS account (xxx) related to the case ID you’ve provided and confirmed this customer is currently on ILDO routes. I’m unsure why SNS would be working for them but Cognito not since Cognito actually uses SNS for the sends. 

If they are facing delivery issues they should engage Premium Support team for assistance.

I will initiate the Premium Support team once I hear an update from you.

[AakashPat]

It has been 15 hours since the ticket and I haven't heard back from them. It is a System Impaired issue which had a 12 hour SLA. Certainly leaves a bad taste in my mouth about AWS Support.

Once I have a response, I will let you know.

[AakashPat]

@shreyansjain, Finally heard back from AWS Support after 36 hours.

I understand that you are facing issues while using Cognito MFA as messages are not getting delivered to your users when using Frankfurth region.

As you are already aware, Cognito MFA messages are sent using SNS in the closest region[1], hence in order to investigate the issue we will need to troubleshoot from the SNS side in eu-west-1 (Cognito Userpools in eu-central-1 is currently using SNS SMS in eu-west-1 as SNS SMS was only recently released in eu-central-1).

As a common reason that causes messages to not get delivered is when the SNS spend limit is reached, I checked the SMSMonthToDateSpentUSD[2] against the Monthly spend limit and noticed that it has hit the default limit of $1.

Unfortuantely, there is no public documentation about which regions rely on which other regions for such situations. Also, there is no way for the users to know which is the closest region to the one they have selected. Upon pointing this out, I got another reply from the AWS Support team.

Yes, Cognito User Pools in eu-central-1 currently uses SNS SMS in eu-west-1 region.
Unfortunately, there is no public documentation that lists the mapping, but it mentions the following[1]:
"SMS messages from Amazon Cognito user pools are routed through the closest AWS Region that's supported by Amazon SNS worldwide SMS delivery."
However as SNS SMS started supporting eu-central-1 region only recently in March 2020[2], Cognito service is yet to update this change for Cognito Userpools in eu-central-1 to use SNS SMS in eu-central-1 region.

I can confirm that there exists a feature request with the Cognito team to update the documentation with this SNS SMS mapping, I have also added the details of this case and how it impacted your business to the feature requests so that the team can understand the issue and prioritize it. Rest assured that your feedback has been conveyed to the team.

[AakashPat]

I have now requested a SNS Sending Limit increase for eu-west-1 region. Hopefully that should resolve my issue. Will confirm once the Limit Increase has been processed.

[shreyansjain]

Thanks for updating @AakashPat

I tried to send Cognito SMS from ap-south-1 and the delivery still failed.

I am pretty sure your issue will get resolved once your spending limit has been increased.

[shreyansjain]

Incidentally, I noticed, some of the MFA texts were being sent from ap-southeast-1 (Singapore) region, even for users based in India.
It might be better to increase spend limt for different regions.

[AakashPat]

@shreyansjain , Indeed my problem was resolved after increasing spending limits in the required region (eu-west-1 in my case).

[AakashPat]

I'm going to close this issue as it has been resolved.

[gvb26]

I am also experiencing this issue. A number of my users are not receiving the code despite the logic of my requests being fine. Ir works for some but not all. AWS support should escalate the issue, put out an update and provide documentation

[FirdousNath]

Facing same issue...it seems like a specific no has limit. I mean if user tries more than 10 times than otp is no received on 11 call.. Facing this during the development of one of my project

[brightfuture]

+1 with this problem
my user pool is in ap-southeast-1
and i've tried to send to US and CN numbers
all failed