This article applies to the BlackBerry® Mobile Data Service.
The maximum number of simultaneous push connections that can be sent at one time on the BlackBerry Mobile Data Server is 1000. Any connection attempts beyond this number will fail and produce a 503 error. This error causes the push attempt to be ignored by the Mobile Data Server. In this situation, your application should throttle back on the number of concurrent connections and, or queue its push requests.
The performance of the Mobile Data Service can be affected by the hardware on which it is running, other services running, the frequency and amount of data being pushed, and other actions being performed by the Mobile Data Service (for example, users browsing with the BlackBerry Browser).