SMS is a best effort protocol, meaning your carrier will do its best effort to deliver the message to you but there may be failures. Sometimes due to high network traffic or spam filters you won't receive the text message.
There are 2 things you can try:
- Install the Mobile App. Opening http://www.authy.com/install on your phone browser will tell you if we have an app for your phone. If we do, simply install it and configure it. Make sure you use the same phone number as you have in the websites you use Two-Factor Authentication for. If you don't see the token there, please use this form to update your number.
- Try with a Phone Call: Phone calls usually arrive much faster. If SMS are not arriving, try receiving the token via phone call. Note, this will require a live phone not behind an extension or going straight to voicemail.