After a user dials in to a Lync Online conference by using an audio conferencing provider (ACP) access number, the user can't hear other users who are connected to the Lync Online conference through their computers, and vice versa.
Open domain federation is required for Lync Online meetings that involve an ACP. This is true because the ACP joins the Lync Online conference as an anonymous user. If domain federation isn't configured to use the Allow federation with all domains except those I block
setting, the audio won't bridge between the ACP and the Lync Online Voice over IP (VoIP) users.
To resolve this issue, take one of the following actions, as appropriate for your situation:
- Set the Lync Online domain federation option in the Lync Online Control Panel or in the Lync Administration Center to Allow federation with all domains except those I block.
- Hang up, and then dial in to the conference again to verify that the correct conference ID is entered.
- Users who are connected through Lync Online should verify that ACP participants are displayed in the attendee roster and that the participants have the correct number.
- Users who are connected through Lync Online should verify that they have a solid network connection and that they don't receive errors about decreased network or audio quality.
- Make sure that the toll number and toll-free number are entered without any punctuation or parentheses when dial-in conferencing for a Lync Online user is provisioned.
- Make sure that the meeting organizer’s Lync 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.
- In a hybrid scenario, run the following PowerShell cmdlet:
Then make sure that the domains of the ACP are added as allowed domains in Lync Server. And finally, provide your external edge fully qualified domain name (FQDN) to the ACP so that they can do the same.
Get-CsTenantFederationConfiguration -SharedSipAddressSpace $true
For more information, go to the following Microsoft websites:
There can be many causes of this issue. These causes include the following:
- Lync Online domain federation isn't configured to use the Allow federation with all domains except those I block setting.
- Dialed-in users entered an incorrect conference ID.
- Dialed-in users are still waiting to join because no Lync Online users have joined the call through VoIP.
- Dialed-in users have a poor connection that's affecting audio quality.
- The Lync Online Data Center can't reach the ACP.
- The toll number or toll-free number was entered incorrectly when dial-in conferencing for a Lync Online user was provisioned.
- The Lync Online meeting organizer is using an ACP account from a different region.
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