Note This article discusses how to troubleshoot Voice over IP (VoIP) and video connections through Lync Mobile 2013. It does not cover issues that occur when you're using Skype for Business Online (formerly Lync Online) together with a Lync to Phone partner to dial out to your designated mobile number (also known as Call via Work, or CVW).
Users who are logged in to Lync Mobile 2013 may experience issues when they try to make VoIP or video calls over Wi-Fi or mobile data connections. Tapping Retry repeatedly does not resolve the problem, and the connection attempt is unsuccessful.
In most cases, audio and video connection issues can be resolved by following these steps:
If a Wi-Fi connection is available, switch to that connection, and make sure that only the Require Wi-Fi for VoIP and video connections setting is selected.
If you're using a corporate Wi-Fi connection that uses a proxy, you may have to configure the HTTP Proxy details in the Lync Mobile 2013 settings.
Skype for Business Online administrators should also make sure that the corporate firewall is configured correctly to allow necessary traffic in and out of the corporate network. For more information, see the following Microsoft Knowledge Base article:
2409256 You can’t connect to Skype for Business Online, or certain features do not work, because an on-premises firewall blocks the connection.
If you're using the mobile data connection, make sure that your bandwidth isn’t limited and that other data-intensive applications work without any problems. Try using a web browser to make sure that you can access other websites.
Skype for Business Online administrators should make sure that the Skype for Business Online users involved are allowed to make audio or video calls in the Lync Administration Center. Also, check the kind of contact that the Lync user is trying to communicate with. If the contact is from another Lync organization or if it is logged in through Skype, audio or video conversations may be disabled. For more information, go to the following Microsoft website: