updated 09:00 pm EST, Tue January 3, 2012
Unclear if problem is hardware-based
The Apple Support Communities forum has begun seeing widespread reports of intermittent audio failure on calls using the iPhone 4S, an issue where recipient can hear the caller but he cannot hear them. The problem is not consistent but happens often enough to be a source of irritation with users. While some have found workarounds, there is no indication in current developer builds of iOS 5 that any fix is in the works in the near-term.
The problem appears to plague both AT&T and Verizon users at least, and is sporadic in nature -- most calls work fine, but occasionally a call will fail to connect the audio until the call is terminated and re-dialed. Some posts have reported multiple back-to-back failures. A similar issue was occasionally seen on the iPhone 4 running iOS 5 but is said to be more rare, suggesting that the problem may have its roots in software or that the newer hardware design of the iPhone 4S has exacerbated an existing issue.
Neither version 5.0.1 of iOS 5 or the current seed builds appear to address the issue. The main fixes in v5.0.1 were aimed at improving battery life and other issues. Users have reported some workarounds for the issue, ranging from simply calling the number back (which generally works) to using a headset rather than holding the iPhone 4S to one's face. Rebooting the iPhone 4S is also said to fix the issue at least temporarily, as has the suggestion of placing calls via Siri. Others have reported that a full restore of the handset's software appears to fix the issue.
A similar issue has been known to occur on other cell phones and even regular "landlines" from time to time, but the issue with the iPhone 4S has become common enough to warrant over 1,600 replies in the main thread on the topic on Apple's site. Thus far the company has not yet officially acknowledged the issue, but may well be in the process of investigating it. [via AppleInsider]