Set up opt-out list for each phone number in AWS console

[terrazoon]

Changing this issue over as new AWS features make this much simpler. We should set up an opt-out list in Pinpoint for each phone number. This will give them independent opt-out lists rather than a combined account-level one.

Eventually we can use Pinpoint API calls to do this automatically, but for now it is few enough numbers to just set it up in the console manually.

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ORIGINAL ISSUE TEXT:

I previously discussed this with Ryan Ahearn. Right now it is quite likely that opting out of one service will result unexpectedly in being opted out of all services.

This is a long term problem and it will be some time before it occurs, but we need to keep track of the association between phones and the services they subscribe to. Obviously we don't want to store any PII so one solution might be as follows:

Make a table with two columns "service_id" and "hash". Every time someone subscribes, a hash of their phone number is added to this table, associating it with the correct service.

Then, before sending, we grab the opt-out phone numbers from AWS and check them against this table, using the service_id of whoever wants to send the message. If we decide that the user has opted out of the service, we reject the message with some useful error message and update the 'provider_response' appropriately in the notifications table.

There might be other ways to do it, but that is what came to mind.

[terrazoon]

This is complicated:

1. Assume that every service has its own sender phone number
2. Assume a user is enrolled in two services and opts out of service A

a. From the standpoint of the carrier, the user is opted out of number A123, but is still opted into B456.
b. From our standpoint, the user's phone number appears on our opt-out list
c. If the user can opt back in using their phone, there is nothing for us to do. The number will disappear from the opt out list.
d. If opting back in requires manual intervention on our part, someone needs to inform us "ah, the user wants to opt back in, here is the phone number" and we can do that without knowing anything about the services subscribed to.

Hence, there may be no work to do for this ticket.

[terrazoon]

Uh-oh.

https://stackoverflow.com/questions/76483827/amazon-aws-opt-in-via-text-start-sms-response

[terrazoon]

It looks like SNS may not support communicate with the carriers regarding opt-in. I texted 'unstop' and ATT says I should be receiving messages, but SNS still has me on the opt out list.

Another thing to try would be:

1. Text STOP on phone
2. Manually clear the phone number from the opt-out list in the AWS Console
3. Send a message and see if it goes through

Expected: No, it doesn't go through because the carrier blocks it

4. Text UNSTOP
5. Send another message

Expected: Message will go through

If the message does go through, then maybe we just need to clear the opt-out list every five minutes and let the carriers handle opt-out and opt-in. From a design standpoint, there's no reason for our app to be involved in managing that (unless there are carrier limitations of some kind etc)