Over the past few months, various phone companies have unveiled "ultra-secure" smartphones, ostensibly in response to growing concerns about digital privacy in the wake of allegations from former NSA analyst Edward Snowden. Now, one company is making that connection plainly obvious by nicknaming its privacy device the "Snowden Phone."

FreedomPop, a company that sells free wireless service, is launching a phone — formally called the Private Phone — that will secure all voice calls and texts with 128-bit encryption. It also provides VPN for anonymous web browsing. Since it runs on FreedomPop's network, which makes use of some of Sprint's unused capacity, the company is letting users change their phone number whenever they want.

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Appropriately, FreedomPop is letting customers pay in Bitcoin, which it says will anonymize the purchase.

The actual hardware is a Samsung Galaxy S II, a phone almost three years old now, so don't expect the best performance in terms of apps and web services. It packs a dual-core 1.2GHz Samsung Exynos processor, 16GB of storage and an 8-megapixel camera. The price is $189, and remember, that includes free calls and text. Data is free, too, but it's limited to 50MB a month, and it lasts only three months. After that, it's $10 a month.

Given the limits in data and hardware, it's clear the so-called Snowden Phone is intended as a supplementary device for when you want a secure device, and not as a person's primary smartphone.

FreedomPop claims the phone prevents third parties from eavesdropping on your communications (including marketers), protects from malware and bypasses "website restrictions" on websites. While encryption does add a layer of extra security, nothing is totally secure: If you use the Private Phone to call landlines, for example, there's no guarantee of protection. Also, it's unclear to what extent government agencies such as the NSA can defeat encryption.

The Private Phone is just the latest in a series of supposedly secure smartphones, which make use of encryption and customized software to build a device with extreme privacy safeguards. The Blackphone, which runs a highly modified version of Android, debuted at Mobile World Congress, and Boeing recently filed a document with the FCC describing a phone that would self-destruct when tampered with.