If you really want to keep your Cisco phones, there might be a workaround but you will
not have the same features on the phones as you would have with Lync-compatible phones. I still would recommend getting new phones but this is a place where you can start:
Cisco offers SIP firmwares for it's phones. You can reflash the phones with this firmware and then register them on Lync using by example a gateway device like AudioCodes. I have to say that reflashing the firmware will require a TFTP server and is
not a very easy procedure.
You would have to configure them on Lync using the pshell command
New-CsAnalogDevice
Technical Specialist Microsoft OCS/Lync & UC Voice Specialisation -
http://www.uwictpartner.be
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