topic Re: ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct. in Collaboration Applications

ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct. 2026

Brad Magnani — Wed, 15 Apr 2026 19:37:00 GMT

All,

Microsoft has previously announced (2023) they will be decommissioning EWS beginning in October 2026 until full deprecation is completed for all customers by April 2027 (https://learn.microsoft.com/en-us/exchange/clients-and-mobile-in-exchange-online/deprecation-of-ews-exchange-online). This affects all Cisco customers running Unity Connection with Unified Messaging integrations with Microsoft Office 365 (now known as Microsoft 365) since EWS is the protocol Unity Connection uses to communicate with the cloud.

Cisco Field Notice: https://www.cisco.com/c/en/us/support/docs/field-notices/743/fn74365.html

Microsoft Graph API is the replacement for EWS and is now implemented in newly available Unity Connection 15 SU4 (15.0.1.14900-45) and later only. Please plan your upgrades accordingly so business is not impacted when October arrives.

Some key points I want to share in hopes it will raise awareness and also save you some time and effort:

NOTE: The migration to Microsoft Graph API applies exclusively to Microsoft Office 365 environments. Integration of Cisco Unity Connection with Microsoft Exchange 2016 and Exchange 2019 on-prem continues to use Exchange Web Services (EWS) APIs for Unified Messaging.

NOTE: Upon upgrading, all existing O365 Unified Messaging Services configured on Unity Connection will be automatically converted to Graph API, EWS will no longer be used. Please make sure you follow the release notes and configuration guides to ensure proper MS Graph API permissions are configured in the cloud prior to upgrade. No changes are required on the Unified Messaging Service(s) from the CUC side. After upgrade, you will see a new "Resource URI" field now populated with a value of https://graph.microsoft.com on your UM services. Here’s an example of what that will look like:

NOTE: Post-migration to Microsoft Graph API, you may experience a synchronization delay of up to 3 minutes between Cisco Unity Connection and Office 365 and vice versa.

NOTE: In Cisco Unity Connection 15SU4 and later releases, message synchronization is scoped to default Outlook mail folders (Inbox/Junk Email/Deleted items) only; messages moved to user-created folders (sub folders) on Office 365 fall outside the supported sync scope and are treated as 'Deleted' from the source folder on Cisco Unity Connection.

NOTE: Starting with release 15SU4, Single Inbox with Microsoft Office 365 does not support the synchronization of sub folders from Cisco Unity Connection to Office 365, and vice versa. It is recommended that you migrate all messages from sub folders to the Inbox prior to performing the upgrade. This new behavior with Graph API is different than the way EWS behaves so there may need to be some user training for those who move voice messages into sub folders.

15SU4 Software Download: https://software.cisco.com/download/home/286331949/type/286319533/release/15SU4

15SU4 Release Notes: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/readme/b_15su4cucrn.html#unified-messaging-with-office-365-using-microsoft-graph-api

15.x UM Configuration Guide: https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/connection/15/unified_messaging/guide/b_15cucumgx/b_15cucumgx_chapter_00.html

Hope this helps!
Brad

Re: ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct.

Roger Kallberg — Fri, 03 Apr 2026 07:52:31 GMT

Great post @Brad Magnani

One question that I've not been able to figure out and since your the definitive CUC expert in here I hope it's okay that I ask it here. If not please let me know and I'll post it as a regular question.

When you have setup a new O365 Unified Messaging Services in Unity Connection there seems to be a delay before the test succeeds to do the discovery for O365. At first I always see this.

Then after some time, undefined how long, I get this.

Is this expected?

This is on a 15SU2 CUC system, so not yet on the version that supports Graph API, from what I understand that's why we're seeing the Failed to locate a Domain Controller via DNS error, that doesn’t seem to have any relevance to anything operational. This error is not seen on a system that has been upgraded to SU4, so my working assumption for now is that it’s something that remains from older configurations that predates the use of application configurations in Azure.

Re: ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct.

Brad Magnani — Wed, 01 Apr 2026 17:40:00 GMT

I've noticed the same thing even in my lab setups over the years. It even happened when I setup Graph for the first time, it failed for a full minute before testing successfully. There's no autodiscovery now with Graph, so I know that's not the cause with SU4 at least. CUC won't just make up failures, it has to receive some sort of bad (or none at all) response from the cloud, but it does seem to be most frequently seen with newly configured UMS for some reason. So I've just chalked it up to all the smoke and mirrors in the cloud all these years 🙂

topic Re: *ACTION* CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct. in Collaboration Applications

*ACTION* CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct. 2026

Re: *ACTION* CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct.

Re: *ACTION* CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct.

topic Re: ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct. in Collaboration Applications

ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct. 2026

Re: ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct.

Re: ACTION CUC UM w/O365 - EWS Deprecation by Microsoft begins Oct.