https://www.macrumors.com/2009/05/18/apple-beginning-high-volume-iphone-os-3-0-push-notification-testing/
Apple Beginning High-Volume iPhone OS 3.0 Push Notification Testing - MacRumors
In an e-mail sent to iPhone developers testing iPhone OS 3.0 betas, Apple announced the start of testing of high-volume Push Notifications using a pre-release...
push notification testinghigh volumeiphone os