Light Reading has dug up some very interesting job postings on Apple’s website. Apple is looking for telephony software engineers to work on iOS. Judging by the list of experience requirements in the postings, Apple is looking to add voice-over-IP (VoIP) capabilities to the iPhone and iPad operating system’s ever-growing feature set.

STOP!

I know what you’re thinking. Apple is finally going to shed the carrier albatross completely and launch its own voice service. But there are plenty of good reasons Apple is hiring VoIP developers that don’t spell the end of the mobile operator’s core business.

In fact, Apple is probably making these hires precisely because it plans to work closely with its carrier partners. The skill set Apple is looking for fits well with the VoIP schemes operators plan to utilize for their next-generation voice services. It’s looking for experience with a set of protocols that may seem like gobbledygook to most people but are well-known to telecom engineers: IP multimedia subsystem (IMS), session initiation protocol (SIP), and real-time transport protocol (RTP), as well as the more familiar wireless network standards GSM/UMTS and CDMA.

The one acronym to focus on is IMS, which is a key component of the One Voice initiative that many of the world’s largest operators have adopted to migrate voice from circuit-switched systems to all-IP voice networks. The U.S. in particular is gung ho about IMS. Verizon Wireless and MetroPCS already use the architecture in their LTE networks, and AT&T and Sprint are implementing IMS to power their future voice and SMS services.

Future iPhones will need SIP-based clients to communicate with those carriers’ IMS cores, so it’s only natural that Apple is hiring experts to build them. I’m sure every other handset vendor is doing the same thing.

But what if . . .

Now I will entertain some of the Apple diehards’ bigger fantasies. There’s nothing preventing Apple from building a VoIP service of its own. Given the big dent Apple had already made in SMS with iMessage and how it yanked video chat right from under the operators’ noses with FaceTime, I wouldn’t be surprised if launching a competing voice service is in Apple’s road map.

The extreme scenarios are: 1) Apple becomes a mobile virtual network operator (MVNO), buying wholesale 4G capacity from carriers, whom it would then relegate to  dumb pipes, or 2) Apple buys its own spectrum and builds its own 4G networks. I  find the first possibility only slightly less ridiculous than the second. Apple doesn’t want to become an operator for the same reasons Google doesn’t want to be one.

The more likely scenario is Apple launches a cross-device VoIP platform that allows customers to trade phone calls among iPhones, iPads and Macs. The beauty of VoIP is that it’s not just voice; it supports all kinds of features, from multimedia and video conferencing to instant messaging and presence that you simply can’t shove into legacy circuit networks. Apple could create an SIP-based communications platform that integrates FaceTime, iMessage and voice into a single multifaceted service, available exclusively to any member of the Apple club.

Whatever approach Apple takes, it’s probably not going to use IMS. It’s such a carrier architecture, coming with all sorts of telecom baggage. Also, Apple has no qualms with walling off its technology and it has a huge customer base to play with: It probably has no use for some stodgy telco standard. It was the IMS core responsible for all of Verizon’s recent network outages, which doesn’t recommend the standard to a company like Apple.

Apple is almost certainly looking for people with an IMS skill set so it can design future iPhones (and possibly iPads and Macs) that work with carriers’ new networks. But that doesn’t preclude it from dabbling in a little VoIP on the side.

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The issue in question is when the iPhone 4S (and according to some reports, the iPhone 4, too) mutes all audio on the caller’s end when placing an outgoing voice call. The person on the other end of the line can hear everything just fine, but on the caller’s end, there’s no ringing sound and no audio from a recipient speaking.

It’s been a problem since the iPhone 4S came out, with most users reporting that it only affects a call every so often, with the majority of calls being placed without problem. In an era where data services are eclipsing voice services on mobile devices, the problem has perhaps understandably taken a backseat to more pressing complaints of battery life issues.

The problem is clearly not isolated, however. A single Apple Support Communities discussion about the bug is now at 109 pages and counting, and the topic comes up in other threads regularly. I’ve encountered it myself (although only once, though I seldom actually make outgoing calls on my iPhone, and most of those are made through a headset, which some have suggested is a workaround for the problem) and until I did a full restore, my girlfriend’s iPhone 4 eventually got so bad that there was never audio on any outgoing calls she made. Some iPhone 4S users are saying a hardware replacement is the only way they could eventually fix the problem.

Apple’s iOS 5.1 release is currently in testing with developers. It presumably will attempt to address remaining battery issue problems, but early reports claim it may not even accomplish that. So far, there’s no direct indication that 5.1 will address the Audiogate (as it’s being called in Apple’s support forums) issue described above, however. I’ve reached out to Apple for comment regarding the issue, but have yet to hear a response.

So far, no fix appears to be a consistent, lasting solution to the outgoing call bug, particularly on the iPhone 4S (a full restore seems to have fixed it on the iPhone 4 for a number of users). Is anyone encountering this problem, and if so, how are you dealing with it?

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