On June 23, users of Microsoft's Lync Online unified communications service were reporting connection problems as of at least 11 am ET.

A number of those affected took to Twitter to ask for a status update on the Microsoft cloud service, which is available both standalone and as part of Office 365. (There's also an on-premises version of Lync.)

Around 3:30 pm ET, the Microsoft Lync account on Twitter acknowledged that "some Lync users in North America are experiencing issues, we are working to resolve." (This was a retweet of an earlier @Office365 acknowledgement of the issue.)

Lync combines voice over IP (VOIP), corporate instant messaging, presence, meetings and video conferencing. Lync is the "inside the firewall" cloud communications service from Microsoft; Skype is the "outside the firewall" complement. Microsoft is working on federating Lync and Skype . Video integration between the two is slated to happen soon (mid-2014), if Microsoft sticks to its schedule.

@MMSInfoTech (Modular Mining Systems IT) claimed that Lync's outage was caused by "a migration of a datacenter by Microsoft" and had resulted in "intermittent connection errors."

"Preliminary Root Cause of Lync Issue: A portion of Microsoft network infrastructure which routes network traffic is in a degraded state," said @MMSInfoTech on Twitter.

I also see users outside of North America -- in Chile and EMEA (Europe, the Middle East and Africa) on Twitter saying they cannot connect using Lync. One user claimed he was unable to sign into Office 365 or repair the issues.

I asked Microsoft for an update on what is causing the Lync problems and when resolution is expected. No word back yet.

Update (4:50 pm ET): Here's Microsoft's statement about what's going on, from a company spokesperson:

"Some users in North America are experiencing issues with Lync Online due to network routing infrastructure issues. In response, engineers have routed a portion of network traffic to an alternate datacenter which has restored service for some of our customers. We are committed to fixing this issue as quickly as possible and expect the service to be restored for all customers soon. Customers can get the latest Lync Online status through the admin Service Health Dashboard."