Users who dial in to Skype for Business Online conferences are on hold indefinitely, or the meeting never starts

To resolve this issue, use one of the following methods, as appropriate for your situation.

Resolution 1

Check the following DNS record: In this record, the placeholder domain represents the name of your destination server. This record is necessary to guide the ACP's servers to the correct destination server. Without this record, the ACP's server can't find the correct destination, and the user is put on hold indefinitely.

This record should be configured as follows:

Record Type:  SRV Record name: _sip Protocol:  _tls Weight: 1 Priority: 100 Port: 443 Destination Host:  sipdir.online.lync.com 

For more information about how to configure the necessary DNS records for Skype for Business Online, go to the following Microsoft websites:

Resolution 2

Verify the formatting of the telephone numbers that are found in the user’s Skype for Business Online settings. To do this, follow these steps:

1. Browse to the Admin Overview page, click Users on the left side of the window, and then open the user who organized the meeting.
2. On the top of the page, click More, and then, under Skype for Business Online, click Configure user settings. There you will find the dial-in conferencing settings.
   
   The Toll and Toll-free number fields are very sensitive to the formatting of the number. When you enter the toll number and the toll-free number, make sure that you don't include parentheses or punctuation (for example, spaces, brackets, hyphens, dashes, and so on), and use only the numeric values 0 through 9. An example of a valid number would be the following:
   4255550187

For more help with Skype for Business Online dial-in conferencing issues, go to the following Microsoft websites:

Resolution 3

Wait for the conference organizer to unlock the conference, or have the organizer add the user to the conference through the Lync client.
 

Resolution 4

Make sure that the meeting organizer’s Skype for Business Online account and the ACP account are configured in the same geographic region. For example, if your Office 365 organization is based in North America, you must use an ACP account that's configured for North America and can't use an ACP account that's configured for the United Kingdom. You can contact your ACP to verify that your account was created in the appropriate region.