It has been discovered that the latest Apple iOS upgrade 7.1 for iPhone, iTouch, and iPad devices breaks current Lync 2013 functionality. Specifically, it has been found that the update creates interoperability issues which causes voice and video to fail when using these devices. Microsoft is aware of the issue as seen in KB2955745 but there is currently no fix or workaround available.
The current solution? Hold off upgrading your Apple devices until a fix is found or you may be without Lync Audio/Video (I say might as Apple iPad Air and iPad Mini do not appear to exhibit the issue).
UPDATE
An update has been released and availabile in the iTunes store and may be foundhere. This update addresses the Apple flaw.
Microsoft has released an update for Lync 2013 that is focused on correcting a single issue – memory leaks during a video call on hardware that has an accelerated H.264 chipset KB2933495. The patch will be offered to all computers via Windows Update and if the situation never applies to you – oh well, just be content to know you are on the latest version of Lync post SP1. There have been issues reported regarding the Gallery View within Lync not working correctly since SP1, but this hotfix does not address that issue. There are two known issues – Persistent Chat file transfers may fail and screen readers may not be able to read the Lync keystrokes.
There are now 4 pre-requisites for the Lync patch which include MSO (KB2727096), MSORES (KB2817624), IDCRL (KB2817626), and Lynchelp (KB2817678).
Additional Notes:
Lync Server 2010 build number is 4.0.7577.225
Lync 2010 Client build number is 4.0.7577.4419
Lync Server 2013 build number is 5.0.8308.577
Lync 2013 Client build number is 15.0.4569.1503
Lync Group Chat build number is 4.0.7577. 4409
Lync Group Chat Server build number 4.0.7577. 4409
Lync Group Chat Admin build number 4.0.7577. 4409
Lync Attendee build number is 4.0.7577.4356
Lync Attendant build number is 4.0.7577.4398
Lync Phone Editions build number is 4.0.7577.4420
Lync 2010 for iPhone build number 4.7
Lync 2010 for iPad build number 4.7
Lync 2010 for Android build number 4.0.6509.3001
Lync 2013 for Windows Phone build number is 5.2.1072.0
Lync 2013 for iPad build number is 5.2
Lync 2013 for iPhone build number is 5.2
Lync 2013 for Android build number 5.1.0000
Lync Basic 2013 build number is 15.0.4420.1017
Lync VDI 2013 build number is 15.0.4420.1017