We use Polycom CX600 phones dedicated for our on-prem Lync 2013, and Im trying to get my CX600 to integrate with my Exchange Online but it doesnt seem to be working.  I can make/receive calls and check voicemail just fine but I'm getting the dreaded "Microsoft Exchange integration unavailable" exclamation which expands to "Connection to Exchange is unavailable due to invalid network credentials".  I try to sign in with the USB-tether but it doesn't change anything.  We are running Exchange 2013 on-prem and Exchange Online via 365 E4.  Exchange 2013 on-prem for all my users and the CX600s are fully functional (I can see calendar, contacts, call logs.).  For my Exchange Online, Ive moved only my account and I am no longer able to see my calendar, contact and call logs on the CX600.  Everything works fine with the Lync 2013 client.  I think this has something to do with it only have a single authentication mechanism on the CX600.  Is there any known workaround to getting EO to work with CX600 phones while having it also continue working for Exchange on-premises?  We are hoping to have a gradual migration to EO where only 50% of our users are moved now and 50% moved much later.  Thank you.

• Edited by Kyle M. Dixon Wednesday, October 09, 2013 2:03 PM

Okay, so I read an article that indicated using username@domain.com to log into Lync when tethering the phone via USB for initial sign-in.  By default, it was populating domain\username which always took, but wouldn't integrate with Exchange.  After using username@domain.com it appears I can see my calendar, call logs and searchable contacts.

• Marked as answer by Kyle M. Dixon Tuesday, October 15, 2013 3:55 PM

If you're using ADFS make sure the certificates on that server are issued from the same Root Authority as your on-premised Lync Servers. The CX600 is failing to authenticate against your ADFS servers before it finalizes it's conversation with O365.

I have implemented this fix several times, the one I am still troubleshooting is customers who only have DirSync and do not have ADFS deployed!

Tony Sollars | UC Architect

• Proposed as answer by Tony S0llars 12 hours 0 minutes ago
• Edited by Tony S0llars 11 hours 58 minutes ago

Thank you Bro..

I solved the problem with Fall Back Certificate:

http://blogs.technet.com/b/applicationproxyblog/archive/2014/06/19/how-to-support-non-sni-capable-clients-with-web-application-proxy-and-ad-fs-2012-r2.aspx

Thanks