What happens to my messages when I am out of coverage?
The wireless data network has a draft store capability that prevents messages from being lost. If you have turned off the radio or have traveled into areas with minimal or no coverage, messages you send will be held at the handheld and messages sent to you will be stored until the signal becomes strong enough to successfully communicate your message out.

This is a very useful feature if you are constantly on the move. You could, for example, compose a few messages while on the subway, issue the send command, and put the handheld back in the holster knowing that those messages will be sent later. The same applies for messages sent to you, the messages will reach you once coverage is restored.

How do I tell whether I am in coverage?
In the top right corner of the Home screen, just below the Battery Life Indicator, you will see the Coverage Level Indicator. Just as with cellular telephones, the more bars that appear, the better the coverage you are in. You can only send messages with 'gprs' is in all caps e.g. GPRS. Small letters 'gprs' or sleeping gprs your device can see the data network but can't register to send messages.

How can I ensure that the handheld has the best coverage possible?
For optimal coverage, keep the BlackBerry handheld in the holster on your belt. When out of the holster, the handheld should be kept in a vertical position in your hands or on a flat surface. Lying the handheld horizontally will reduce the ability to send and receive messages successfully and will consume additional battery power. (In low coverage areas ofcourse)

What network do 8xx & 9xx BlackBerries work on?

RIM Wireless Handhelds operate over nationwide wireless data networks. The RIM 950 and RIM 957 operate over the Mobitex network, operated by service providers such as Cingular Interactive in the United States and RogersWireless in Canada. The RIM 850 and RIM 857 operate over the DataTAC network, operated by Motient Corporation in the United States and Bell Mobility in Canada. Free nationwide roaming is also offered.