In early 2015, Google implemented a warning to protect Android users against accidentally getting charged for SMS spam. This means that the first time a user responds to a message from a shortcode, such as the one xMatters uses, a system warning message (like the one below) cautions users that responding to a short code "may cause charges" to their account.
The good news is that these charges are just the normal costs for sending SMS messages - there are no extra fees to worry about when responding to xMatters.
The bad news is that cancelling this message (even without selecting the Remember my choice option) a few times might result in your responses not being sent to xMatters. Some users have reported that the warning message stops being displayed after three or four appearances, and there's no indication that the response is not being sent.
The best way to deal with this is to make sure that users know that the first time they encounter this message, they should select the "Remember my choice" option and then tap Send. This will add the short code for xMatters as a safe target in their phone, and they won't see the warning again.
If you have already ignored the warning message, you can resolve this problem by enabling the "Premium SMS Services" option on your phone:
- Go into your phone Settings, and scroll down to Apps (or Applications, or Applications Manager, depending on your phone).
- Go to the All list of apps, and locate your SMS messaging app.
- Open the messaging app settings, and locate the Permissions section.
- Find the setting named Send premium text message (or something similar), and set it to Always allow.
- You could also set it to Ask, and then use the "Remember my choice option" the next time you are prompted.
You should now be able to send SMS messages to the xMatters short code.