Within the Communication Preferences section of your Account settings, you can enable your account to receive SMS updates.
These updates include the verification code you need to login to your account, order status updates and shipping information.
To enable this, you will click on the Edit button, and then type in your mobile number and then click the box next to "Yes, please send me SMS updates about my order and account to my mobile number" and Click update.
You can un-enroll in these notifications any time, by clicking Edit, unchecking the "Yes, please send me SMS updates about my order and account to my mobile number" box, and then clicking Update.