Hi all, We have just deployed Lync, and except a few things everything seems to be ok. What is not working is some functions of lync using exchange web services, such as voice mails. EWS status in lync never becomes OK. It is always EWS not available, retrying connection. What is interesting is that Lync can get voice mails of user and shows them, but never updats and until you signout and signin again, we can not view new messages. So I traced http connections and saw what the problem is. Some of http calls from lync client to exchange web services (/ews/exchange.asmx) fails. It gets HTTP 500 error. But some of them are ok with HTTP 200. As soon as lync gets http 500 after. We have two active directory sites each contains two-server cas array and one mailbox server. Both sides are internet facing through reverse proxy. HTTP 500 error details: <?xml version="1.0" encoding="utf-8" ?> - <s:Envelope xmlns:s="http://schemas.xmlsoap.org/soap/envelope/"> - <s:Body> - <s:Fault> <faultcode xmlns:a="http://schemas.microsoft.com/exchange/services/2006/types">a:ErrorNoApplicableProxyCASServersAvailable</faultcode> <faultstring xml:lang="tr-TR">Exchange Web Services are not currently available for this request because there are no available Client Access Services Servers in the target AD Site.</faultstring> - <detail> <e:ResponseCode xmlns:e="http://schemas.microsoft.com/exchange/services/2006/errors">ErrorNoApplicableProxyCASServersAvailable</e:ResponseCode> <e:Message xmlns:e="http://schemas.microsoft.com/exchange/services/2006/errors">Exchange Web Services are not currently available for this request because there are no available Client Access Services Servers in the target AD Site.</e:Message> </detail> </s:Fault> </s:Body> </s:Envelope> Dou you have any clue what the problem may be? Regards, Suat.

Hi Suat, I would suggest you seek the solution in the Lync forum: http://social.technet.microsoft.com/Forums/en-US/category/ocsPlease remember to click Mark as Answer on the post that helps you, and to click Unmark as Answer if a marked post does not actually answer your question. This can be beneficial to other community members reading the thread.