Mobile World Congress is inching closer and closer, and it's expected that Nokia will show off a new handset or two at the big show, especially since we didn't see much of anything from the Finnish firm at the Consumer Electronics Show last month. It's not known exactly what Stephen Elop and Friends may have up their sleeves for MWC, but today a couple of new Lumia models have been revealed that could be on tap for the event. A filing on the website of POSTEL, an Indonesian regulatory group, has revealed listings for a "520/RM-914" and "720/RM-885" from Nokia. 

While details on the 520 and 720 are still fairly light, their model numbers suggest that they could be lower-end Lumia handsets like the Lumia 510 and Lumia 710 that launched last year. It's possible that one of these units could be the "Nokia Flame" that we saw listed on a recent-leaked T-Mobile roadmap. The Flame is thought to be an entry-level Windows Phone 8 device with a 4-inch display and 512MB RAM, and with a rumored launch date of April 24, the Flame could be a device that Nokia would introduce at MWC and then bring to T-Mobile a couple of months later.

In other mysterious Nokia news, a design patent found by LiveSide from the company may serve as a teaser for an upcoming Lumia handset. As you can see below, the drawings depict a phone with a curved back, rectangular camera area and a divider on the face with a space below the screen for some capacitive keys. The design is actually fairly similar to a device that pops up at around the 0:38 mark of a purported Nokia concept video from 2011. Nokia filed for this design patent in December 2011.

It's not known exactly when or if this design might actually be used on a shipping product, but now that Nokia's been granted the patent, it's certainly possible that we could see a Windows Phone 8 handset pop up later this year sporting this very look. What do you think of this design? Does it have the look of a phone that you'd consider adding to your gadget arsenal?

Via Engadget, POSTEL, The Verge, LiveSide, U.S. Patent and Trademark Office