In this video, we cover the two-line functionality of the DX900 by inserting two SIM cards into the phone. It turns out that the implementation is quite simple.

To start, each line is labeled as “1″ or “2″ – with the second correlating to the SIM card that doesn’t allow for data access. The phone will tell you the individual signal strength of each line. In theory, you should be able to use two different carriers with this device (such as T-Mobile and AT&T), just as long as the bands are supported.

Then, when you receive a call, the phone tells you on which line that call is coming. When making a call, you can choose either line 1 or 2. It would be nice if you could label each line with a custom title, such as “Personal” or “Business.”

Finally, since SMS are routed through GPRS and thus a particular phone line, you can choose SIM1 or SIM2 when sending text messages.

Overall, the implementation of the two-line function works quite and well and is easy to keep track of.

In case you missed it, check out the unboxing and hardware tour.