Exchange 2007 and Nortel CS1K Message Waiting Indicator – The Cheap Way

Geomant MWI Software would have cost around £2000

Looked for an alternative and came across Freemwi

The Developer Justin was a great help.

Below is the communication we had…….


Sorry for the delay in response. Don’t know if you have figured it out yet, but it will be hard to help you with out more information.

My initial guess is that you are using the email address instead of the UPN. e.g. the users UPN is [email protected], but email is [email protected]

If you can send me a copy of the user CSV, screen shots of the General, and Account tabs, in Active Directory Users and Computers, what your impersonation account user is and the print out of this command: “Get-MailboxPermission -Identity [email protected] fl” I will be in a better position to help you.

One other trouble shooting tip, in a browser you should be able to go to the OWA site and impersonate the user:[email protected]

then login with you MWI user: e.g. [email protected], it should open his mailbox.


As mentioned earlier, I have now tried to roll freemwi out to more users but am getting strange results…..
For some users I am getting
Cannot impersonate: does user exist?

Whereas others are fine.

The users are in the same active directory ou, have the same Mail Store, are in the same groups,
Cannot find a difference that would cause this problem.I have re-run the extended rights impersonate ps command and the impersonate rights seem to have already applied

If you can shed any light it would be much appreciated.
I know this is pretty much unsupported but I do appreciate the help you have given so far.


Glad to hear you got it working.

Assuming you are following this:

There are two additional things you need to do
First you have to run the service as a user:

and second most importantly you must run the service with the application path of the exe:
Note the AppDirectory key

That is how I got mine running as a service.

When I have more time I will write up some detailed instructions. Let me know if that is enough or if you need me to elaborate.


Good News!

We have successfully installed freewmi and it is now working.

The instructions you supplied were spot on and easy to understand and follow.

The only thing we did have to do was install .net 2.0 (might be worth putting into your documentation)

The only problem we had was with proxy authentication not being passed thru freewmi.
We added a non authenticate rule to our isa server and this did the trick.

We currently have it configured and working for about 20 users.

I plan to expand this to a further 100 within the week.

The one thing I did try was to get freewmi running as a service using instsrv.exe and srvany.exe but it did not run the freemwi.exe.

I will try to work on this and let you know if I have any progress.

Have you come across this request from anyone else?

Other than that an excellent application.

Many thanks for all your help


Thank you for contacting me. I look forward to hearing how you make out, and if you are willing to provide me with notes on the integration with the CS1k that would be greatly appreciated.

I have had a few other people inquire about the CS1K but none have implemented it yet, they were in the pre-testing phase.

This is what I sent them:

Note: this it is not tested, and is based on my reading of the documentation on Nortel’s website.


Here are a few tips that might help you to implement it with the CS1K:

Note: I am not very strong on the Nortel side of things, so this might not be fully correct.

Since you can’t run this on a server running the Exchange UM Role, you will have to run it on another box, e.g. Another non-um Exchange Server, File Server, Domain Controller, etc. (I have mine running in a Hyper V machine); You will have to allow it to send SIP UDP messages to Sip Proxy Server (SPS) (Assuming you are doing Direct SIP), When you create a Gateway Endpoint for Exchange, you will also want to create a Gateway Endpoint for the MWI Server, except you will want to choose SIP UDP, it should look something like

Endpoint Name FreeMWI (Unique Name)
Endpoint authentication enabled Authentication Off
Static endpoint address
SIP support Static SIP endpoint
SIP UDP transport enabled Checked
SIP UDP port 5060

You will also need to steer traffic down the Gateway Endpoint See page11, and then 21 of the next link for RLB and Steering Code setup and for adding a route entry. See Below
for the MWI DN

This is based on this document

User telephones should be configured with MWA (Message Waiting Allowed) Class of Service to receive MWI Lamp notification.

The Node configuration page (in Element Manager) needs to be configured with information for both the MWI Application DN and the MWI Dialing Plan. The configured MWI DN and MWI Dialing plan should be administered as a valid DN on the Call Server to ensure routing back to the SIP gateway; this is required if the ISDN Facility Response is to be sent back to the SIP gateway.
You can find this under Element Manager: System -> IP Network -> Nodes: Servers, Media Cards.
Click to expand the Microsoft Unified Messaging tab as illustrated in the diagram above.
If MWI application is used for Lamp Status Update, configure the properties:
MWI Application DN See above
MWI Dialing Plan CDP (I am assuming)
Note: FreeMWI sends out the MWI as coming from the person it is sending it to, e.g. if Lamp should be turned on for 4501 then it shows it is coming from 4501 to 4501, this should not be a problem but if it is I can always recompile a version that sends from your Subscriber Access Number, just let me know if you want to try this.

This has some MWI configuration information

Hopefully the above makes sense as I was mainly trying to get my thoughts out, but basically you need to mirror the configuration for Exchange except with a different DN, Gateway Endpoint, and SIP UDP.

Hopefully that is all the configuration you need on the CS1K.

When troubleshooting I would first make sure FreeMWI is properly configured and monitoring the Mailboxes (as I know this works), then I would configure the CS1K, and use Wireshark on the MWI server to see that FreeMWI is sending out the MWI packets to the CS1K and see the response. Feel free to send me packet captures if you wish.


I don’t see any reason we can’t get my program to work. I am willing to help out where I can, and I look forward to hearing how this work out.

Thank you,


Was very pleased to find your application out there and am hoping to implement here at our college.

Our set up is as follows;

Nortel CS1000 server
MS Exchange 2007 with UM Voicemail

I will let you know how we get on.

If you have any further info regarding configuration on the CS1000 I would be grateful if you could pass it on.

4 Thoughts on “Exchange 2007 and Nortel CS1K Message Waiting Indicator – The Cheap Way

  1. Hi, I am trying to get this working and the applications exits with a 401:Unauthorized when trying to login to my Exchange's EWS/Exchange.asmx page. If I browse to it manually with Internet Explorer I get a user/password prompt, and I am able to login with the user/password specified in the exchange.csv file.Any clues?

  2. False alarm, the app is now working, re-unzipped everything. But it is not turning my light on (Pun intended) 😉 I'm running a CS1000 and have followed the steps outlined here. I have configured my MWI DN to 7502 and created the needed DSC and RLI to go to my SIP Trunks and I have also created a STATIC SIP Gateway in my NRS, and added the 7502 route to it. Any clues?

  3. Have a look at this product as well.$500 one off payment regardless of numbers. Well supported. I gave him documentation on how this can be configured in a cs1000 environment which he has posted on his site. Very slick software and fully AD integrated. Highly recommended.

  4. don't suppose anyone still has a download of this still knocking around, the site has been down for over 6 months now.

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