A Simple Test For Verifying Mobile HDVoice

nexus-5-200pxT-Mobile has been supporting mobile HDVoice for over a year. However, my sense is that not very many people are actually experiencing HDVoice. If they are, they might not even know it.

For example, two of my associates have the Google/LG Nexus 5 handsets on T-Mobile’s network. Both are the sort of people who would hear and appreciate the difference that HDVoice makes. That said, both were initially of the impression that the Nexus 5 did not support HDVoice on T-Mobile!

This gave rise to the idea that we should devise a simple way to verify that a call was in HDVoice. If convenient, this would allow anyone interested to make a call between two handsets and know with certainty that the devices and call path was actually delivering HDVoice.

Devising such a test turns out to be very easy in a world of smart phones. All you need is a tone generator or a recording of a specific continuous tone.

Traditional narrowband calls a la PSTN standards are bandwidth constrained to pass only 300 Hz- 3.4 Khz. In contrast, wideband calls pass 50 Hz – 7 KHz. Therefore, a 5 KHz continuous tone can be heard across an HDVoice call, but not heard at all over a narrowband call.

NB-vs-WB-5kHz-Tone

A 5 KHz tone is easily generated using a freeware tools like JJ. Bunn’s AudioTool for Android, an app that I quite like, although there are numerous such apps available. A tool that created a tonal sweep from < 3KHz to > 5 KHz could also be useful in demonstrating the loss of tone across the upper boundary of a narrowband call path.

I recently used this simple test to verify that the Nexus 5 is HDVoice-capable on T-Mobile’s network. I took my wife’s N5 into one of the nearby T-Mobile stores and made a call from it to another Nexus 5. I then used my Nexus 4 to generate a 5 kHz tone in front of one of the Nexus 5’s. That tone was clearly and rather annoyingly heard coming from the other Nexus 5. This test works well enough even when using the speakerphone mode of the Nexus 5.

I didn’t want to try the patience of the store staff so I didn’t try making calls from the Nexus 5 to many other handsets while on-site. That said, I know for certain that calls from the Nexus 5 to my older (getting sad now) Nexus 4 do not pass the test tone, so are not HDVoice enabled.

In truth this little test would work for any two phones you care to try, even wireline desk phones. The simple fact that a smart phone app can be used as a reasonably precise tone generator makes the test conveniently portable, and a handy way to annoy the mobile carriers retails staff.

The more adventurous among you may wish to test further, trying various Bluetooth headsets to see if they fit into a mobile HDVoice ecosystem. I may yet try that…another day, once the ringing in my ears has passed.

  • It’s my understanding that you talking about T-Mobile’s support of HDVoice on their cellular network for standard (non-SIP) mobile calls. Are you aware of any Internet resources that list HDVoice-compatible handsets? Thanks!

    • mjgraves

      At the macro level GSA has a document dated March 2014 that lists 329 mobile handsets that officially support AMR-WB. You can fins it here; http://www.gsacom.com/hdvoice/ but to get it requires you to be logged in. Registration is free.

      T-Mobile is less helpful with respect to HDVoice. As I mentioned previously (http://www.mgraves.org/2014/03/mobile-hdvoice-post-three-acts/) in order to determine if any handset they offer is HDVoice capable you must visit the support page for that handset and look at the “tech specs.”

      • Michael, thank you very much for the info. I registered on the GSA website and was pleased to find my handset (Huawei Ascend P1 U9200) listed as HDVoice-capable. It’s interesting that official specs don’t mention HDVoice at all, only Dolby Mobile 3.0 Plus support. I’m not sure if the latter implies the former, but even if it is, most consumers wouldn’t be aware of it.

        I use this phone on T-Mobile network, so, according to your post, I should experience HDVoice quality, provided the other party has an HDVoice-capable phone. If I’m correct, do I need to change any settings to enable HDVoice on my side?

      • (My comment below was marked as spam – I guess, it’s your Disqus’ settings to auto-mark as spam posts with links. Therefore, I replaced the link to GSMArena’s website with just their name. Hope it’ll get through this time.)

        Michael, thank you very much for the info. I registered on the GSA website and was pleased to find my handset (Huawei Ascend P1 U9200) listed as HDVoice-capable. It’s interesting that the manufacturer’s official specs don’t mention HDVoice at all, only 5.1 Dolby support (GSMArena lists it as “Dolby Mobile 3.0 Plus”). I’m not sure if the latter implies the former, but even if it is, most consumers wouldn’t be aware of it.

        I also wanted to remark on your post “Mobile HDVoice; A Post In Three Acts”. Your advice in Act 2 on visiting the support section of the T-Mobile’s website to check handsets’ HDVoice capabilities is not totally accurate. The advice works only for phones offered by T-Mobile. People, like me, who use unlocked global phones on T-Mobile network, will not be able to find their phones there and, consequently, check the HDVoice compatibility. You might consider updating that section with a link to the GSA document that you kindly posted in your comment above.

        I use this phone on T-Mobile network, so, according to your post and the GSA documents, I should experience HDVoice quality, provided the other party has an HDVoice-capable phone. If I’m correct, do I need to change any Android settings to enable HDVoice on my side?

        • mjgraves

          Oh, no. It’s not enough that the phone be HDVoice capable (AMR-WB) on a network supporting AMR-WB. If that were the case then my Nexus 4 would support HDVoice on T-Mobile’s network, which it does not.

          The carrier must allow the phone to use the relevant codec on it’s network. I don’t have the specifics of how that’s done. I presume that there’s some kind of codec whitelist on a per handset basis.

          • Hmm, that’s strange, considering that T-Mobile officially declared and market their support for HDVoice. By the way, if you don’t mind sharing, what is the average DL/UL speeds that you’re seeing on T-Mobile data network?

          • mjgraves

            All carriers support for HDVoice is listed relative to specific handsets. The list was very short at launch in 2013. It’s longer now.Only supported models will actually place HDVoice calls.

          • Yes, I understand that. But, as Nexus 5, your Nexus 4 (unless it’s not E960 model) is in the list. That is what I was referring to as “strange”. You didn’t answer about the speed. The reason I asked is that I don’t see the promised speeds. For example, my smartphone and cellular data network both support HSDPA (HSPA+) rated at up to 21 Mbps, but, I rarely see the speed above 2 Mbps. I am on T-Mobile’s $30 “5G data / 100 min. voice” BYOD plan.

          • mjgraves

            The Nexus 4 is the E960. T-Mo simply decided not to support HDVoice on Nexus 4. Today I see 13 mbps x 1.3 mbps on T-Mo here in Houston.

          • I see. Thank you for the replies and your time, Michael!

          • Guest

            Hmm, that’s strange, considering that T-Mobile officially declared
            and market their support for HDVoice. By the way, if you don’t mind
            sharing, what is the average DL/UL speeds that you’re seeing on T-Mobile
            data network?