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Cisco Unity Connection MWI extensions

Unanswered Question
May 13th, 2014
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Hello guys.. 

A quick one.. I'm testing the Message Waiting Indicator (MWI) on my Cisco Unity Connection Server.

When I configured the MWI extension I just created one (the ON one)... then I went to Unity and put the same extension number on the ON and OFF MWI field... 

I tested it and everything worked fine -------> if I Got a message the led goes red and if I delete it or save it the led goes off..

I'm still reading a little and I see that the right way to configure this thing is to use two MWI extension, ON and OFF.. but, does anybody have a clue of why did it work with only the ON one? I mean.. the red light went off when I deleted the messages.... How does the MWI works? Cisco is not very clear about this on the docummentation

Another thing would be, Is there a max number of lamps that one of those extensions can control or am I cool with 2? 

Thank you..

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Overall Rating: 4 (1 ratings)
Jaime Valencia Tue, 05/13/2014 - 20:29
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You won't find any documentation of the underlying MWI process, but yes, you need two MWI DNs for this to work as expected. I assume that at some level, the DN just relays a signaling and it doesn't check if it's the same or different DN.

You can create as many pairs as you need if you have more than one integration.

DAVID L GARCIA ... Tue, 05/13/2014 - 20:43
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Hello Jaime..

Thank you for your reply...

Do you know if there is a limit of phones that MWI's extensions can control? I have like 125 users with voice mails. (The voice ports and the Extensions are all configured with the right partition and CSS so they can reach each other). 

I've already created two (On and OFF) as everyone does and I put those extensions on the Internal partition (as almost every other extension), is there any recommendation? like putting the extensions on the same partition as the Voice Mail?



Jaime Valencia Tue, 05/13/2014 - 20:50
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No limit, you only need a pair per integration.

The integration guide addresses the partition question for MWI DNs.

martino-cisco Fri, 05/23/2014 - 07:21
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Hello Jaime,

I just came across this discussion and as you are experienced with Unity I was hoping I could share a problem with you.

Currently MWI is set to come on when a new voicemail comes in and go off when the message has gone off. At the moment I have a problem where users don't get the MWI light blinking when they receive a new message and are only made aware of it by looking at their email inbox.

Ironically, sometimes MWI loses synchronization and the light comes on even when there is no message.Normally refreshing the status or Resynchronizing fixes that for me. 

My main problem is the fact that when they receive a new message, MWI doesn't come on. Also, when they press the 'messages' button on the phone, the message is there, so I believe it is not getting deleted from the voicemail repository.


Any ideas on this please?

DAVID L GARCIA ... Fri, 05/23/2014 - 08:01
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Hello Martino,

Did you check if your Unity Connection has the MWI configured?

Go to CUC, Telephony Integrations, Port-group (Check if MWI is enable and if you configured the right DNs


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