HD Voice

Following announcements earlier this month from both AT&T and Verizon, T-Mobile announced today it’s introducing Voice over LTE support starting with the Seattle market:

So I’m thrilled to congratulate my team on the launch of Voice over LTE (VoLTE) in the Seattle area for our existing LG G Flex and Samsung Galaxy Note 3 and Galaxy Light customers. Our friends at MetroPCS were the first to launch VoLTE in the U.S. back in 2012, and we’ve been working hard on a LTE Advanced version of VoLTE, which we plan to roll out to more T-Mobile customers throughout the coming year.

T-Mobile’s CTO Neville Ray noted that the new technology, which brings voice calls onto the same LTE radio layer previously reserved for data, will allow “faster call setup times (almost twice as fast as a non-VoLTE call setup) and the ability to enjoy lightening fast LTE data speeds while on a call.” It will also support the HD Voice or wide-band audio feature that Apple already supports. Ray explained how the technology works:
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AT&T already announced plans to turn on HD Voice, aka, wideband audio support, later this year through a carrier update for iPhone users in the US. Today, iTweakiOS announced an update for one of its hacked carrier profiles that it claims will allow AT&T users to access HD Voice, as well as the recently announced CMAS government and Amber alert update, ahead of a full roll out of the feature later this year.

This hack fixes the reported issue of unstable HSPA+ speeds/signal and iPad users having trouble updating and losing all signal. This hack enables, along with the previous enabled features, HD Voice for all iPhone models running on AT&T so users can now use the UMTS/HSPA/HSPA+ network for HD qaulity calling on their 4S and 5. This hack also enables Release 7 HSDPA speeds for the iPhone 4S, giving it a new maximum theoretical downlink of 21Mbps, which AT&T does indeed support. Signal improvements from the previous release have not changed and are still present in this release along with unthrottled LTE and HSPA+.

Apple has actually supported the feature since the iPhone 5 launched last fall, but only around 20 international carriers currently support the feature. Unfortunately, the HD Voice feature, even with the hack, won’t yet work for all users, as AT&T is still currently in the process of rolling out support:
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