While there was much talk of wearable technology and large-screen smartphones at last week's Mobile World Congress (MWC), another trend has begun to emerge: secure phones that ensure your privacy.

Ever since Edward Snowden blew the whistle on global surveillance operations run by the U.S. and other governments, the privacy of citizens' messages, phone calls and emails has become a major concern.



With that in mind, U.S.company FreedomPop released a "privacy phone" this week -- dubbed the "Snowden phone". The phone is a Samsung Galaxy S2 that Los Angeles-based FreedomPop has morphed in to a call- and data-encrypting device. It offers secure calls and text messages, and a built-in private network to surf the internet anonymously.



(Read more: An NSA-proof phone?)



On FreedomPop's website, the advert for the new phone reads: "Privacy is a right not a privilege. Protect your privacy from hackers, government agencies and spyware."



Customers can pay for the phone with digital currency bitcoin to ensure anonymity, and can also request a new phone number as often as they want.



FreedomPop was established in 2011 and has launched a price-assault on the main U.S. mobile networks. It offers privacy phone users free unlimited voice and text messages for the first three months, as well as 500 megabytes of memory space. It charges $10 a month for the package of services thereafter.

Bevy of secure phones announced

FreedomPop's privacy phone is just the latest in a list of recent secure smartphones to be announced. However, at $189, it is cheaper than other devices which offer to encrypt phone calls and emails.

Geeksphone's Blackphone, for instance, comes in at $629. It was unveiled at MWC and is due for release this summer.

(Read more: Taking on BlackBerry: The mobile that promises privacy)

Boeing also launched its tamper-proof Black Smartphone last week, aimed at government agencies and contractors who need to keep communication and data secure. Boeing said it had spent 36 months developing the device, which is not yet commercially available. Its retail price is yet unknown.

(Read more: Boeing offering 'black phone' for secure communications)

Ben Wood, chief of research at CCS Insight, warned CNBC that the new secure phones would not be completely immune from government surveillance.



"All these devices are taking advantage of the current anti-NSA zeitgeist," Wood told CNBC via email.



"They take advantage of current fears about government and commercial snooping, but the depth and complexity of surveillance techniques means they are unlikely to provide truly secure communications. The encryption on the phones means that what you say is protected and the content on the device is safe. But the NSA can still capture metadata, such as the identity of the mast your phone is using, and therefore your location."

Neil Mawston, executive director at Strategy Analytics, argued that ordinary customers' security concerns were insufficient to determine their mobile-buying decisions.

"The top-of-mind issues for smartphone buyers worldwide are normally suitable pricing, cool branding and attractive styling," Mawston told CNBC.

"If a consumer can afford a smartphone, and it comes from the right brand, and it looks good, those factors will usually override any security concerns."

With that in mind, Mawston said the main customers for secure phones would be government agencies and contractors. "Secure smartphones for consumer users worldwide will remain niche," he said.

Even if most customers are unconcerned about securing their phone from the reach of "Big Brother", they may be interested in securing it from other users, particularly in the case of theft, suggested Wood.

"The introduction of the touch ID fingerprint sensor on Apple's iPhone 5S has prompted a flurry of interest in biometrics on mobile devices," Wood said. "Although this was not a new innovation…the adoption by Apple has led to other manufacturers following this approach."

Wood added that MWC had showcased a wide range of biometric products that could be of interest to the ordinary smartphone consumer.

"There were product demonstrations from companies such as Hoyos Labs, whose HoyosID uses periocular, iris and facial recognition. Bionym showcased its Nymi wristband, which stores security data and personal information, and recognizes its owner from their heart's unique rhythm," he said.

—By CNBC's Kiran Moodley. Follow him on Twitter @kirancmoodley