Notice: This website is an unofficial Microsoft Knowledge Base (hereinafter KB) archive and is intended to provide a reliable access to deleted content from Microsoft KB. All KB articles are owned by Microsoft Corporation. Read full disclaimer for more details.

External users can�t join Lync Online conferences anonymously or as guests

View products that this article applies to.


When you try to connect to a Microsoft Lync conference by using the Microsoft Lync 2010 Attendee client, you may experience one of the following symptoms:

Symptom 1
The attendee clicks the Join online meeting link for Microsoft Lync Online and then receives the following error in the Lync 2010 Attendee client:
Reference ID 101 (source 238)
There was a problem verifying the certificate from the server.
Symptom 2
The attendee isn't joined to the meeting with presentation capabilities such as sharing.

Symptom 3
The attendee clicks the Join online meeting link for Lync Online. However, the Lync Online client doesn't load. Instead, the Microsoft Lync Web Application loads.

↑ Back to the top


For symptom 1
To resolve symptom 1, add the necessary DNS records to resolve the issue.

Check the _sipfederationtls._tcp.domain record and _sip._tls.domain record in DNS (where the placeholder domain represents the domain suffix of your user ID). These records are required so that anonymous users outside your organization can locate and connect to the correct Lync Online servers. These records should be configured as follows:
Record Type: SRV Record name: _sipfederationtls Protocol: _tcp Weight: 1 Priority: 100 Destination Host: Record Type: SRV Record name: _sip Protocol: _tls Port: 443 Weight: 1 Priority: 100 Destination Host:
For more information about how to configure the necessary DNS records for Lync Online, visit the following Microsoft websites:
Wiki: Ensuring your network works with Lync Online
2566790�Troubleshooting Lync Online DNS configuration issues in Office 365
For symptoms 2 and 3
To resolve symptoms 2 and 3, the user should either switch their default browser to Windows Internet Explorer or copy the Join online meeting link from their invitation and then paste it in their browser.

↑ Back to the top

More information

For symptom 1
The Lync 2010 Attendee client can't correctly locate the Lync Online servers because of missing SRV records in DNS. These records enable anonymous users to join Lync Online conferences.

For symptoms 2 and 3
The user is using Google Chrome as their default browser. The Lync Browser Helper add-in isn't configured for Google Chrome when the Lync 2010 Attendee client is installed.

The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, about the performance or reliability of these products.

↑ Back to the top

Still need help? Go to the Office 365 Community website.

↑ Back to the top

Keywords: o365, o365a, o365p, o365022013, after, upgrade, o365062011, pre-upgrade, o365m, o365e, KB2693625

↑ Back to the top

Article Info
Article ID : 2693625
Revision : 11
Created on : 9/18/2013
Published on : 9/18/2013
Exists online : False
Views : 294