How can I upgrade WhatsApp Tier?
Tier upgrade is something that is done automatically as per the documentation below:
To summarize, a business’s phone number will be upgraded to next tier if:
1. Its quality rating is not low, and
2. The cumulative number of users it sends notifications to adds up to twice its current messaging limit within a 7-day period.
Once the business reaches this threshold, it will be moved to the next tier. The minimum amount of time that this upgrade can occur is after 48 hours, provided the business is sending messages up to their current limit every day. To keep message quality high for end users, we ask that your business follow our tier system for upgrading the messaging capacity of its phone numbers.