Log Name: Application
Source: MSExchange
Unified Messaging
Date:
1/14/2015 10:27:09 PM
Event ID: 1079
Task Category: UMCore
Level:
Warning
Keywords: Classic
User:
N/A
Computer: server4.mytestlab.com
Description:
The VoIP platform encountered an exception FailureReason = 0
Microsoft.Rtc.Collaboration.CallOperationFailureException:Remote
participant did not offer required SRTP support --->
Microsoft.Rtc.Collaboration.OfferAnswerException:Remote participant did not
offer required SRTP support
A similar error was given by the Lync client:
A quick Google search did not turn up anything useful. Looking at the Lync client logs, I noticed that the conversations were not encrypted.
Using http://msdn.microsoft.com/en-us/library/dd948772(v=office.12).aspx as reference,
The candidate list in the out Invite did not contain the following three lines:
a=cryptoscale:1 client AES_CM_128_HMAC_SHA1_80 inline:CG6lTObp+llK1yu|2^31|1:1
a=crypto:2 AES_CM_128_HMAC_SHA1_80 inline:X8PSqo+1vhl9R8NxBs1jTVuXNlGr|2^31|1:1
a=crypto:3 AES_CM_128_HMAC_SHA1_80 inline:sHbs569BxAuxz9sVDAVSqQ6|2^31
And the SIP 200 ok showed that the peer connection did not support encryption.
To make a long story short, the issue was a site level Media configuration setting that was configured to "DoNotSupportEncryption."
Using set-CsMediaConfiguration, I updated the setting to "SupportEncryption"
