Apple Inc. (Nasdaq: AAPL) is looking for telephony software engineers to work on new iOS products, according to job postings on the company's website, but it's not clear from the job descriptions exactly how the device maker plans to support voice services on LTE smartphones.

Will Apple follow the current consensus among mobile operators and support voice over LTE (VoLTE), which is based on IP Multimedia Subsystem (IMS), or will it go its own way?

According to an Apple spokesman, that's not a question the company would answer.

One of the job descriptions, calls for someone with "experience in SIP, real-time transport protocol (RTP), and VoIP related protocols," as well as "familiarity with telecommunication network architectures: GSM/UMTS, CDMA, VoIP, IMS."

The mention of IMS in a job posting doesn't indicate that Apple will ultimately support IMS in its operating system, but it does suggest that the company is working on a voice strategy for all-IP LTE mobile broadband networks.

Analysts are divided about how Apple should handle LTE voice and IMS support.

"I don't know what their position is on IMS, nor does much of the industry," says Heavy Reading Senior Analyst Gabriel Brown. "But interoperability is, and will remain, a foundation of mobile communications."

"There's a view they could try and do an end-run around the telecom industry and create their own communications services eco-system by developing Facetime and iMessage," he adds. "No doubt there's some merit to that view, but ultimately everyone benefits from cross-platform communications services."

According to Dean Bubley, founder of consulting firm Disruptive Analysis Ltd. , IMS just doesn't seem to fit with Apple.

"IMS to me is pretty much dead against how Apple views how communications should be," says Bubley. "I don't think that they'll hand the keys to the communication kingdom back to the operator community when they have been such poor custodians of the customer experience. Operators have been asleep at the wheel."

He suggests that Apple might instead develop a communication system that is compatible with IMS but not support full IMS and by doing so it would meet mobile operator requirements while at the same time maintain control over its own communications.

"I think they would put something in iCloud that acts as a transcoder or border function," he says. "I would consider some kind of cloud-based solution ... it would be IMS-ish."

Another point, adds Bubley, is that not all of Apple's products are SIM-based cellular devices and that has implications for how it will support voice in a consistent way across all its devices.

"Whatever Apple does, it will want [voice] to work on its cellular and non-cellular devices," he says. "Any voice platform will need a non-SIM mode … [like] an over-the-top extension of IMS. Apple won't want a completely different voice experience on the iPhone and a Wi-Fi only iPad."

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— Michelle Donegan, European Editor, Light Reading Mobile