Are there any third party MWI products for Exchange 2007 which are known to work with pbxnsip? I haven't found any which list pbxnsip as a supported IP PBX.

I have tried manually sending some SIP NOTIFY messages to pbxnsip with the relevant data, but it always responds with 404 not available. The SIP OPTIONS command does not list NOTIFY as supported. Is there a setting I have to enable somewhere in PBXnSIP for it to accept unsolicited notify messages from a SIP gateway (i.e. Exchange)?

As it doesn't appear to support these messages I am wondering if it is possible for a 3rd party product to achieve this?

Yea, it is amazing that the Exchange (a great product) had a blackout on MWI. The way you are supposed to get the MWI is to poll the Exchange server through SOAP messages. IMHO that is a joke.

Then if you actually know that there is a SIP account that has a MWI, then the next step is to tell the PBX about it. Here we go with the next SOAP message. Because pbxnsip also supports SOAP! But of course the two SOAP messages are totally unrelated.

I really don't know... If someone can give me an example on how the SOAP messages to Exchange look like it is probably easier to do the SOAP natively in pbxnsip than to use 3rd party software (which is sometimes even more expensive than the IP-PBX!).

The Exchange team would everyone do a favor by using the well-established RFC for MWI.

Yeah, it is amazing that Exchange 2007 just "forgot" about this feature. Fortunately it is sorted in Exchange 2010.

If pbxnsip can turn on the MWI lights via a SOAP message, then I'm sure we can hack up something to get it working as we are a .NET software company.

Can you provide a link to any docs about the SOAP APIs for PBXnSIP, and a sample SOAP message that turns on the MWI light? This approach did cross my mind before but I was unable to find any docs on it, so I started exploring SIP solutions as mentioned above.

Currently, we have "SetExtensionParameterRequest" SOAP api, which can be used to set the voice mail indicator on the extension. But MWI is not sent to the phones on this change in the versions that are available for the public. But we have already added this on a beta version.

Thanks for the info. Can you let us know what version number will have this feature?

Also, are there any plans to support the SIP notify approach for Exchange 2010 compatibility?

I am not very clear about the SIP NOTIFY plans at this moment.
If I understand the requirements correctly from your message, when someone leaves a voicemail, Exchange 2010 will send a NOTIFY to the PBX and PBX should send the MWI to the corresponding phone. Is that correct?

This is the SIP NOTIFY that I have constructed from reading some SIP docs and packet sniffing what some of the third-party Exchange 2007 MWI tools send (where 192.168.0.3 is the Exchange server and 192.168.0.10 is PBXnSIP):

NOTIFY sip:101@192.168.0.10 SIP/2.0
Via: SIP/2.0/TCP 192.168.0.3:5060;branch=z9hG4bK.37ace54681;rport;alias
From: <sip:101@192.168.0.3>
To: <sip:101@localhost>
Contact: <sip:101@192.168.0.3>
Call-ID: 54681@192.168.0.3
CSeq: 54681 NOTIFY
Event: message-summary
Subscription-State: active
Content-Type: application/simple-message-summary
Content-Length: 49

Messages-Waiting: yes
Voice-Message: 1/0 (0/0)

I would imagine that Exchange 2010 will do something very similar to this, and that it may also require the PBX to support these sort of NOTIFY messages without having a subscription (unsolicited NOTIFY).

Currently these messages are rejected by PBXnSIP with 404 not accepted.

How can the PBX know it is not a spoofed packet from somewhere in the network? Do you know if Exchange supports authentication (e.g. Digest)? We have no problem with unsolicited NOTIFY, but we want to make sure we don't generate a security leak.

Yes, I can see that is an issue, and I'm not sure how Exchange handles the installation.

It is frustrating though that other PBXs allow you to basically turn off the security on this though to get the MWIs to work, and PBXnSIP doesn't - having a slight internal security risk is better than no MWIs at all.

Well, we have to do it right. Not sure if the other PBX want to end up in a security chaos where everyone in the network can turn LED on and off and program nice animation patterns for SIP phones in the office.

Microsoft also takes security very serious. I am sure that there is a way to get this working in a safe way and we don't have to worry about this.

Cisco consider it secure enough in their CallManager product.

Assuming the MWI is going to be provided by a third party product though, can you allow PBXnSIP to accept these messages with some form of authentication?