MWI from Exchange 2010 SP1 UM to Lync 2010

I was planning to write a post on how Exchange 2010 SP1 UM is able to send Message Waiting Indicator (MWI) to Lync 2010, but then I discovered that this is already covered in great detail in the Exchange 2010 SP1 documentation.

What I will add to the description is a little more how it works on the Lync side. The UM server sends a SIP NOTIFY to the Lync Server, when a new voice message is received for a user. On the Lync side the user needs to be Enterprise Voice enabled. An excerpt of such a NOTIFY is shown below:


From: <>;epid=EDDFA7F3EE;tag=f03dc3ff8

To: <>


EVENT: message-summary


USER-AGENT: RTCC/ MSExchangeUM/14.01.0218.012

CONTENT-TYPE: application/simple-message-summary

Messages-Waiting: yes


Voice-Message: 8/3

The Lync Server will transform this into a BENOTIFY to the user containing the MWI category. An excerpt of such a BENOTIFY is shown below:

BENOTIFY sip:;transport=tls;ms-opaque=a98bb6354a;ms-received-cid=7C7300;grid SIP/2.0

To: <>;tag=fd7ce0df4d;epid=e0bc6cec3d

From: <>;tag=23480080


Require: eventlist

Content-Type: application/vnd-microsoft-roaming-self+xml

Event: vnd-microsoft-roaming-self

subscription-state: active;expires=6978

<roamingData xmlns="" xmlns:cat="">

<categories xmlns="" uri="">

<category name="mwi" instance="0" publishTime="2010-10-26T07:42:42.387" container="1" version="32" expireType="static">

<mwi xmlns="" messageWaiting="true" unreadVoiceMailCount="8" readVoiceMailCount="3"/>


Some time after reception of the BENOTIFY the client will connect to Exchange 2010 SP1 through EWS and fetch the details of the voice messages and display them. The MWI is used on Lync 2010 Phone Edition running on devices like Polycom CX600 and Astra 6725ip.

Comments (2)

  1. Anonymous says:

    Hi Jens,

    How to configure the MWI feature in MS Exchange 2010 UM for the Polycom CX600 phone ?



    Jens: You only need to set the UM dial plan attribute as described here You also need to make sure that EWS is working for the devices. No configuration is needed on the Lync side.

  2. Anonymous says:

    If a third party application sends a NOTIFY request for MWI to the Lync server, will it convert it into a BENOTIFY and send it to the communicator client?

    In other words, can a application other than Exchange set / clear MWI on Clients?



    Jens: We only support Exchange UM setting the MWI, so I won't speculate what might work 🙂

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