Reflective/Session Traversal Utilities for NAT (STUN) – STUN ‘reflects’ or returns the public NAT address to the Skype for Business client e.g.Candidates – A list of possible IP addresses that could be used to establish an audio or video path.

Interactive Connectivity Establishment (ICE) – Process used to discover and exchange candidates to find the most optimal audio or video path.

For example, its the thing that tells the server you want to make a call by sending a SIP INVITE.

SIP signalling – simply put, it’s the control traffic.ICE is the overall process that helps discover and exchange ‘candidates’ to finds most optimal audio and video path. To do this, Skype for Business uses Interactive Connectivity Establishment (ICE). To reduce the likelihood of this happening, Skype for Business will attempt to find and use the shortest path between users – This can result in two users on the same network sending their audio and video traffic directly to each other, all the while, the SIP signalling traffic continues server/client. On the other hand, any significant delays to audio and video traffic will be immediately noticed by the user and could disrupt the call. Any delays (latency) in this traffic is typically unknown to the user.

SIP signalling and control traffic in Skype for Business takes the run of the mill approach – traffic is routed directly between server and client. This article will give you some new tools to help you troubleshoot a Skype for Business audio not working issue.Īudio and video establishment in Skype for Business takes a different approach to most network traffic. Understanding how Skype for Business establishes audio and video (media) paths can improve your ability to troubleshoot these tricky issues. This is a common issue in Skype for Business deployments.

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