You can choose where your six-digit sign-in code goes. Email still works exactly as it did. If you would rather have it as a text message, you can now use your mobile number instead — useful if your email is slow to arrive, or if you are signing in from a phone and would rather not switch apps.
Codes are sent from SIMCOAI, through the same protections as everything else we send. The code itself is never written into our own records, there is a firm limit on how many can be sent to one number in an hour, and premium-rate and satellite ranges are refused outright — those exist to stop somebody running up a bill by asking for codes they never intend to use.
Replying to one of those texts now gets an answer pointing you at somewhere useful, and replying STOP stops them. Before this, a reply reached nothing at all.
What changed
Text codes add a choice of delivery channel for the six-digit sign-in code. They are useful when a customer can reach their phone more easily than their mailbox during sign-in.
The change concerns how the code arrives rather than the role of the code. It is still part of the account’s sign-in process and should be used only in the flow that requested it.
Before and after
Before this update: The sign-in code was delivered by email; a customer waiting for a delayed email had no text-delivery alternative through this feature.
With this update: Customers can choose mobile delivery where supported while email remains available. Replies to the texts receive guidance, and STOP opts out of those texts.
What it means for you
Use a mobile number you control and can receive messages on. Check the sign-in screen’s options if you are not receiving a message, rather than repeatedly requesting codes.
Sending is limited to prevent abuse, and unsupported premium-rate or satellite number ranges are refused. Choosing text does not mean codes can be sent without limits or to every number type.