All these Lync Phone Devices, will not support TLS version 1.2.
Polycom: CX500, CX600, CX3000
HP: 4110 and 4120
Mitel/Aastra: 6721ip and 6725ip
Lync Phone Devices can’t connect to Office 365 after 31. October 2018, because only TLS 1.2 will be support from Microsoft after these date!
Audiocodes introduce a replacement program for these devices. The offer can be found on the Audiocodes website at: