Customers around the world – most especially KPN (News - Alert) subscribers in the Netherlands, it seems – wonder when Apple and RIM will support HD voice in their handsets. Meanwhile, Microsoft (News - Alert) has managed to keep pace in supporting wideband voice in Windows Phone 7.  What does the future hold?

Apple, being Apple, has been tight-lipped about future features for its iPhone (News - Alert). The company's current model for HSPA networks, the iPhone 4 S, certainly contains all the right hardware “stuff” – dual mics for better noise cancellation and Audience's voice processing algorithms placed directly on the A5 CPU rather than in a separate chip. Going back a generation, the iPhone 4 has the same features with the exception that Audience has a dedicated chip to work its voice processing magic.

It's in the software where Apple has fallen short, not providing support for the AMR-WB codec used around the world in 2G GSM, 3G/4G (depending on your marketing department) HSPA+ and forthcoming LTE (News - Alert) networks for HD voice.  

From the rumors I've heard, Apple will likely roll out support for AMR-WB with the iPhone 5, with support across all cellular technologies – CDMA, GSM & HSPA, and LTE. In addition, I wouldn't be surprised to see the iOS rolled out with the iPhone 5 provide HD voice support for the iPhone 4 and 4 S models, with earlier iPhone users having a 50/50 shot.

Apple fans will argue the phone already supports HD voice via soft clients, such as its own native FaceTime video client and CounterPath's Bria, which supports G.722. Strictly speaking, that's true, but the convenience of simply dialing a number or tapping on a contact to make an HD call without having to wonder if the person on the other end can receive a SIP or FaceTime call is very convenient.

RIM, to be polite, has issues. The company certainly is aware AMR-WB is out there – especially with Bell Canada's launch of HD voice in the Great White North last month – but doesn't seem to be in a hurry to support it. Managers may be more focused on updating their resumes than adding features, but France Telecom (News - Alert) has expressed its annoyance at a lack of HD voice support out at Mobile World Congress last month.

The underdog in the mobile handset races is Microsoft. However, the company has made HD voice available for customers/carriers with Windows Phone 7, featured on the Nokia Lumia family. People tend to ignore/underrate Microsoft when it comes to consumer electronics, but the Xbox 360 is a force to be reckoned. Given the relatively rapid turnover of handsets every two years (or less) in most markets, Microsoft could quickly grab market share – and having HD voice onboard definitely helps.