I recently started using Orange’s new roaming service that allows you to roam on T-Mobile’s network, in the same way as you might roam around networks when you are abroad. So far experiences are very positive. The phone remains on Orange most of the time, which is fortunate as 3G/HSxPA signals are only available via the Orange network. However, when a signal isn’t available, it seems to roam fairly quickly and efficiently onto T-Mobile’s network. The phone sees this as a roam: the same “R” symbol appears on my Desire’s screen. Charges are allegedly exactly the same as via Orange, so in theory it shouldn’t cost anything extra (although I’ve yet to see a bill since I’ve had it turned on).
The only potential disadvantage I can see is that in order to get data service on T-Mobile’s network (which is GPRS only), I have to switch off the protection on my Desire that stops it using the data on a roamed network. This does have the slight danger that I might forget to turn this off when travelling to a foreign network and being charged large sums. However, I’m prepared to take this risk/inconvenience for the benefit of being able to do the roam.
In general, a great new service from Orange, assuming they keep up the same quality of service. Now, if only they’d stop piling on crappy “added value” apps via their phone, and innovate on network features (of which this is a great example).