The sample apps all assume that the device is connected via MDS to a BES server, which is true in the simulator (using the MDS simulator). However when testing on a device you will need to use a different transport if it is not connected to a BES server. For example, on your 8900 you could use Wi-Fi or Direct TCP (and sometimes WAP2 depending on the carrier).
You'll need to modify the URL passed into Connector.open() so that it has the correct arguments to specify the type of network connection to establish. See this thread for more information about how to establish an HTTP connection over the various transports.