This update takes Phone Edition to 4.0.7577.4487 / 4488 & adds SHA-2 support.
There doesn’t seem to be an over-arching KB that goes into any more detail (that I can find), just David Paulino’s post on the UC Lobby page on TechNet:
This update for Microsoft Lync Phone Edition devices adds support for the SHA-2 suite of digest hash and signing algorithms for connections from clients. The SHA-2 protocol uses digest lengths of 224, 256, 384, or 512 bits. After you apply this update, Lync Phone Edition devices can be connected to a Microsoft Lync server that contains a certificate that is issued from the same Certification Authority (CA).
Download the relevant CAB files from here:
- Polycom CX500, 600 and CX3000 (4.0.7577.4487)
- Aastra 6721 and 6725 (4.0.7577.4487)
- HP 4110 and 4120 (4.0.7577.4487)
- Tanjay (4.0.7577.4494)
9th December 2015: This is the initial post.
10th December 2015: Updated version numbers to reflect changes in the KB articles since yesterday. (Thanks Richard!). Firmware loaded into Lync 2013 using http://www.ehloworld.com/1217 and all version numbers above confirmed correct.