BlackBerry Curve 8310 and 8320

Overall, this is a reasonable GPS application and it should get you where you need to go. It doesn't have the sophistication of smartphone navigation software like CoPilot (which is due out for BlackBerry soon) or TeleNav's BlackBerry software, (which comes on the T-Mobile 8310), but the monthly subscription is fair value. If you do choose to upgrade, the 8310 is powerful enough to run navigation software well and the GPS receiver works well (in applications other than BlackBerry Maps).

The other good news is that using the GPS doesn't rob you blind of battery power for receiving emails and making phone calls.

Starting from a full charge and navigating in an urban environment for 90 minutes (including ten minutes in a building that blocked the GPS signal) only ran the battery down to 85 per cent. RIM seems to be managing the GPS radio as aggressively as it manages EDGE; if you don't get a satellite signal in a reasonable amount of time the 8310 stops trying rather than ramping up the radio and running down the battery. That's frustrating if you're trying to navigate in a difficult location, but the best choice for a multi-function device.

And 85 per cent doesn't mean you need to rush off for a recharge either. We beat RIM's claimed four hours of talk time by nearly an hour. Assuming you're not on the phone for five hours you can expect to go three or four days between charges without using the GPS and if you're not navigating every day you should still get two days of email on your travels. The Curve is already an all-round performer and adding GPS to the 8310 adds a useful extra string to its bow.

Wi-Fi what-for

The dark grey finish on our review sample 8310 looks sleeker and somehow less plastic than the light silver of the 8320; the only other way to tell them apart is that the legend next to the mute button on the top of the case reads WI-FI rather than GPS on the 8320.

Adding Wi-Fi to the 8320 should give you VoIP calls and free browsing but how well this works is up to your mobile operator. The ideal would be VoIP calls over any Wi-Fi connection switching to standard voice calls seamlessly when you get out of range, and the necessary UMA technology is present, but that would mean less voice revenue for the operators. If you get the 8320 from Orange, you can only make seamless calls over an Orange broadband connection at home (the Orange Unique service). Alternatives like EQO, Jajah and iSkoot give you cheap calls by running a VoIP call in the cloud and phoning your number; it's nice to have the option but it's needlessly complicated and there's minimal advantage to using Wi-Fi for this as the phone radio has to be on anyway. You can run GTalk on the 8320 but that only gives you IM, not calls and we weren't able to get the Gizmo5 service working at all.

The sensible alternative for the enterprise is to use RIM's own BlackBerry WLAN solution with your IP-PBX; that way users will get free VoIP calls and PBX features like mailbox access and conference calling too. If you're not planning to invest in a solution that will specifically support BlackBerry devices for VoIP, the 8320 is much less exciting than it ought to be - the service matters more than the hardware here.

It's not really worth using Wi-Fi to download email because the efficient compression of RIM's push email system means that most messages download speedily enough, even without 3G. Pages do download over Wi-Fi more quickly than over EDGE, but there's not as much of a difference as you might expect.