Shortly after the announcement of the iPhone 5 on Wednesday, it quickly became apparent that the dual-mode CDMA/LTE version of the forthcoming device would in theory have been one of the most desirable models to own, owing to its multiple LTE band support compared to the European and Asian dual-mode UMTS/LTE variants. However, recent news regarding the limitations of the new CDMA/LTE model have since come to light, and might be enough to blunt usability for all but the most dedicated owners.

First Limitation: No Simultaneous Voice/Data on CDMA

Unlike select CDMA/LTE Android smartphones which allowed simultaneous voice and data use owing to the integration of separate chipsets for CDMA and LTE that also had the effect of making devices physically larger, Apple’s implementation of CDMA and LTE on the same baseband chipset for the iPhone 5 means that functionality will be limited to handoffs between voice and data sessions, meaning that you won’t be able to use LTE while on a phone call. No software updates will be able to circumvent this limitation as the hardware itself does not allow for concurrent voice and data sessions affecting both the Sprint and Verizon versions.

The only alternative for simultaneous voice and data use at this point on the CDMA/LTE iPhone is to use Wi-Fi in place of LTE when available, as that functionality is contained on a separate chipset within the device. Cold comfort to those who were expecting the simultaneous voice/data functionality to remain in place and tick the box for those that took advantage of such functionality.

Second Limitation: No Wideband Audio (HD Voice) Support

When Apple announced the addition of what it calls Wideband Audio for its voice calls, it did not immediately define what carrier compatibility would consist of, only mentioning that 20 carriers were signed up to support the capability during the initial announcement, since everyone including me assumed that it was merely rebranding the HD Voice system currently being deployed by select carriers around the world.

Within the last couple of days however, the extent of the compatibility for the feature has been confirmed to only be compatible with UMTS 3G networks operated by the initial 20 carriers confirmed to support the service, which leaves out the CDMA carriers, including Sprint and Verizon. Sprint initially confirmed that it would indeed support Wideband Audio, only to correct the statement yesterday with the admission that it would not be able to support Apple’s implementation owing to its HD Voice rollout on CDMA 1x Advanced, which would not allow it to roll out the service for the iPhone 5, which is being supported by UMTS 3G.

With these two exceptions for the CDMA iPhone, they miss two key features that may not be necessary to every iPhone user and potential new customer, but those that have expected these features to take advantage of them will have to make adjustments to work around the lack of the features in these versions. They may not be enough to be dealbreakers, but they do serve as an example of where Apple’s priorities lie in terms of network technology support.