According to the Verge, Microsoft will most likely launch two new low-end devices, as the numbering scheme suggests.

The Lumia 640 XL is presumably a bigger version of the Lumia 640.

Leaked information about the devices suggests that the Lumia 640 will be a 5-inch device with 1GB of RAM and 8GB of storage, all powered by Qualcomm's Snapdragon 400 processor.

Rumours also suggest that Microsoft is placing an 8-megapixel camera at the rear of the device and a 1-megapixel camera at the front.

Several big phone companies launched new high-end smartphones and other wireless gizmos, hoping to challenge US giant Apple in a big year for wireless gadgets.
Samsung, fellow South Korean firm LG and hip Chinese maker HTC timed their smartphone launches to grab the attention on the eve of the Mobile World Congress, the world's biggest telecoms trade fair, in Barcelona, Spain.
In a head-on challenge to Apple's popular iPhone 6 which was released last year, Samsung came out fighting with the Galaxy S6, a smartphone with a touchscreen that curves around the edges and has a wireless charger.
It also presented the larger S6 Edge, a "phablet" somewhere between a tablet and a phone in size.