Last night at CES 2013, T-Mobile CTO Neville Ray announced that AMR-WB (Adaptive Multi Rate Wideband) was enabled on the operator's network, instantly allowing capable phones to place higher quality voice calls over the cellular network between T-Mobile customers. This announcement makes T-Mobile the first GSM/UMTS based network in the US to enable AMR-WB, but not the first operator in the US to deploy "HD Voice," as Sprint has been rolling out 1x-Advanced's EVRC-NW (EVRC-Narrowband Wideband) wherever their network modernization and LTE upgrades are.

HD Voice enables calls with a much wider dynamic range. AMR-WB is a direct successor to AMR-NB (narrowband) and offers higher frequency bandwidth of up to about 8 kHz (16 kHz sampling) as opposed to AMR-NB's 4 kHz. I'm unclear what bitrate or coding mode T-Mobile US is using, however I'd be willing to suspect that T-Mobile has probably gone for enabling the full AMR-WB range of bitrates. I have to say I'm impressed with T-Mobile US' constant leadership over AT&T with UMTS upgrades in the US. AT&T currently runs AMR-NB at 5.9 kbps for comparison, not even the full allocation AMR-NB bitrate. Update: It's possible that T-Mobile is using the 12.65 kbps AMR-WB bitrate. 

This upgrade was made active last night, and all mobile-originated and mobile-terminated calls on T-Mobile between phones that support AMR-WB should now use the mode, subject to other factors that normally affect multirate codecs such as coverage profile and network load. T-Mobile has called out the Samsung Galaxy S 3 and HTC One S as being examples of two such phones that definitively already include AMR-WB support, although any phone that exposes the capability on network attach should work just fine.

I placed a number of calls between T-Mobile users last night to try and gauge any perceptible difference. I've previously heard AMR-WB demos and run loopback calls on the Anritsu base station emulator, and there is a perceptible difference. I originated a call on a Nexus 4 and terminated it on a Nexus 4 with both on T-Mobile, which sounded excellent, and then between an iPhone 5 (attached to PCS WCDMA here in Las Vegas) and a Nexus 4, which also sounded very different than an AT&T AMR-NB originated and terminated call. I need to do more testing back home, but T-Mobile's claims that this is live right now and working seem credible, calls sounded crisp and much more intelligible than some of the AMR-NB calls I've been on.

Source: T-Mobile

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  • adamquesada - Wednesday, January 9, 2013 - link

    It seems the Galaxy Nexus supports WB, but can anyone confirm if its activated by default on the phone?
  • mrseanpaul81 - Wednesday, January 9, 2013 - link

    Can anybody confirm that the Galaxy Nexus supports WB?
  • dferbr - Thursday, January 16, 2014 - link

    I have tested this feature extensively and the result is that Galaxy Nexus does support AMR-WB but I was able to make it work only when using some particular basebands. As far as I can tell it works when you use some of the korean, japanese or australian basebands. However, I ran into issues which I was not able to resolve. These issues included occasional call drops or sound dropouts as the phone sometimes had to switch from WB to normal mode because of signal quality. I am not sure whether the cause is rather low quality of T-Mobile network here in Czech republic or if it is a problem of the phone because since I bought this phone I started to experience these issues and even after I got a replacement they did not seem to go away. Because these issues happen more often when using AMR-WB I finally switched to some other baseband that does not support AMR-WB but seems more stable with my operator's network.
  • amdwilliam1985 - Wednesday, January 9, 2013 - link

    What about international Samsung Galaxy S3 on TMobile network?
  • deltatux - Wednesday, January 9, 2013 - link

    The Nexus S, Galaxy Nexus and Nexus 4 have the capabilities for HD Voice. WIND Mobile in Canada (my carrier) have HD Voice enabled for these devices and they use AMR-WB.
  • eagle63 - Wednesday, January 9, 2013 - link

    So I'm in the service mode on my Galaxy S 3 (*#0011#). Should I be seeing something in here to validate that I'm picking up AMR-WB? I do see an entry here that says:

    "SpeechVER: EFR FR not used"

    No idea if that's related or not..
  • eagle63 - Wednesday, January 9, 2013 - link

    ok, I disconnected from WiFI and now I DO see "AMR 12.2 kbit/s" at the bottom of the service mode page. So I take it I'm good then?

    This does bring another question though: If I'm connected to a WiFi hotspot, am I NOT getting HD voice? If yes, I assume that means that AMR-WB voice goes over the data network? (packet data instead of circuit-switched??)
  • dferbr - Thursday, January 16, 2014 - link

    AMR-WB is just a codec and setting for voice calls. It still has to go through your carrier's network. If you were using some SIP service then it would be able to transfer the data via wifi but this does not concern standard phone calls.
  • DeeMann - Wednesday, January 9, 2013 - link

    Do these calls ride on thier HSPA+ network - wht happens to two HD capable devices outside that environment; also +1 on the Wifi question
  • iwod - Wednesday, January 9, 2013 - link

    HD Voice, Now we need VoLTE Asap.

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