How does the usage-based SMS account balance work?
With EasyRoutes Premium, we offer usage-based SMS notifications in select countries. This is done through creating usage charges that loads up a EasyRoutes Usage Balance. SMS messages sent by route stop events will count against your usage balance based on the recipients' location.
Approving an App Spending Limit
When signing up for a Premium plan, the plan approval page has an "App Spending Limit" section. This sets a maximum possible value that a shop can be charged based on SMS usage: 
You are only issued a charge when the usage balance is added. This is done via the Manage Usage Balance modal. The usage maximum is required in order to add credit to your balance.
Adding to EasyRoutes Usage Balance
The Manage Usage Balance modal is used to add usage charges and update the balance used to charge for SMS messages. You can access this modal when you attempt to enable any SMS notification event settings on the Email & SMS Notifications tab or using the "Manage balance" link on the General tab.
Selecting "Add $15 to my balance" will apply a charge of $15 USD and update your usage balance. You will see usage charges on your bill. SMS messages sent by route stop events will count against your usage balance based on the recipients' location.
See How much does SMS usage cost? for a list of available recipient countries and prices per message segment.
Enabling the "Automatically top up my balance when it runs out" checkbox will automatically apply $15 USD charges when the usage balance reaches $0.
You can view your SMS usage and usage balance remaining on the Settings -> Help tab.
We will also attempt to remind you if your balance is running low on a route page if you are manually adding credits to your balance.
Appendix: Opt-in for Existing Premium Users
Existing Premium users will see an option on the Email & SMS Notifications tab in Settings to "Turn on SMS Notifications":
Selecting this button will launch a plan approval page to be able to accept usage-based charges.