Folks in the U.K. can now pre-order an unlocked and SIM free version of the Lumia 550. As listed on Carphone Warhouse, Microsoft's new entry-level Windows 10 smartphone costs the equivalent of $137. Installment options are at $11 per month.

The availability of the pre-order might be limited to the U.K. as of the moment, but at least we now have an idea on when the Lumia 550 will start shipping. The listing indicated that free delivery is set to arrive on Dec. 8. The shipment date is exactly two months after Microsoft unveiled its trio of Windows 10 smartphones at a press event in New York back in October.

According to Phone Arena, the Lumia 550 rocks a 4.7-inch 720 x 1280 LCD display with pixel density of 314ppi. Qualcomm's Snapdragon 210 chipset is on board towing a quad-core 1.1GHz CPU alongside the Adreno 304 GPU.

In the memory department, there's 1 GB of RAM and 8 GB of native storage expandable up to 200 GB via micro-SD card slot. The lights are kept on by a 2,100 mAh battery that offers 16 hours of talk time and could theoretically last up to 672 hours or 28 days when the device is left idle. Music playback is quoted at 60 hours while video playback is at seven hours.

Its five-megapixel rear camera features LED-flash, autofocus, touch focus, digital zoom and geo-tagging. It is also capable of recording 1280 x 720 Full-HD videos at 30 frames per second. Selfies and video calls are taken care of by a two-megapixel front-facing unit.

While the Lumia 550 and its higher-ended siblings have been officially unveiled by Microsoft, there are rumors suggesting that an alleged Lumia 650 will be showcased very soon. For the time being, specs of the fourth Windows 10 smartphone from Microsoft have remained unconfirmed.

The new mobile operating system might be a pet project of Microsoft but it doesn't mean it's exclusive to the Washington tech giant. Asian mobile makers such as Acer, Freetel and VIAO have displayed their upcoming Windows 10 smartphones at a Microsoft event back in October, K-Tai reported.

Acer introduced its 4.5-inch Liquid M330 handset, which had the same RAM, CPU and GPU as the Lumia 550.

Freetel showcased a prototype model of its upcoming a mid-range offering known as the Katana 02. It has 2 GB of RAM, 16 GB of internal memory and a 2,600 mAh dry cell.

Meanwhile, Sony Corporation offshoot VIAO merely brought a mock-up smartphone to the occasion. However, it stated that its Windows 10 offering is still being tested and will launch in early 2016.