Czech developer PoweryBase is claiming that Apple is intentionally blocking push notifications to users of unlocked iPhones.
PoweryBase, makers of several applications that use Apple's push notification service, said 80 percent of its customer support complaints are coming from a very small minority of its customers. All of these customers are using unlocked iPhones.
The developer explains that when a push application requests an ID from the Apple server, the iPhone receives a unique token. Once the token is received, push notifications proceed as you would expect. The process only takes a few seconds to complete.
However, PoweryBase says on unlocked phones they have seen the Apple server not respond at all. This just leaves the user's app in limbo until it times out.
Apple representatives were not immediately available to comment on the developer's claims.
It's not clear at this point if other app developers are having the same problems with unlocked phones or if this is an isolated incident in that country or with that application.
Push notifications were implemented as part of iPhone OS 3.0 and allow developers to "push" information to your phone. For example, this means that you don't need to launch an application to be alerted that news headlines have been updated. The push service will pop up an alert and let you know as soon as it happens.