What does HD Voice sound like on a mobile VoIP call?

Here in the U.S., we may be ahead on LTE subscribers, but when it comes to voice quality on our mobile phones, we’re still lagging behind. Network operators in other countries have adopted HD Voice and wideband audio codecs to provide a better voice calling experience: Think Three UK, Telestra and T-Mobile USA’s parent company, Deutsche Telekom. In 2011, these and other carriers around the world took mobile voice calling to the next level.
I’m starting to get a taste of these voice calls, because I’m using¬†Bria’s Android 4.0 client on my Galaxy Nexus. I previously wrote about how I’m essentially getting free voice calling through VoIP on my Galaxy Nexus with a data-only SIM card. For $30 a month, I have unlimited data and texting, so I’m using the data plan for VoIP calls and supplementing it with Wi-Fi calling in the home office.
Android(s goog) natively supports the SIP standard for VoIP, and while I can (and was) using the standard Android phone client for calls, Bria has already won me over. There are many reasons, but for now, the main one is the wide number of audio codecs supported. Instead of a “narrowband” audio codec, which limits the frequency range of a call, Bria has several “wideband” codecs (some available as an in-app purchase), bringing richer sound as well as a reduction in background noise.

To give you an idea of the difference in call quality, I recorded three different scenarios: a standard cellular to cellular call, a cellular to VoIP call over 3G, and a cellular to VoIP call over Wi-Fi.¬†The best call experience with Bria is a true SIP to SIP call because the audio doesn’t have to be converted for a voice network during the call. I don’t have a recording of that, because I’d need two SIP accounts to call myself from one phone to another.
People I’ve called have said the voice quality is fantastic on their end. That’s a win for me, as are the essentially free calls I’m making and receiving. Once voice calls actually become data — watch for this next year with Voice over LTE, or VoLTE — I expect start to see call quality improvements, provided carriers allow for the extra bandwidth used by the wider range audio codecs.
As another example, here’s an HD Voice demo that Telestra put together to illustrate the difference: