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. (emphasis above is mine) I use Boom on my own MacBook Air and it does a reasonable job of increasing the internal speaker volume beyond what I was getting with the built-in volume. From the videos on YouTube, Hulu, your favorite music playing on iTunes, to voice applications like Skype, iChat and your favorite Games, Boom can boost them all.

A mixer is a great means of recording podcasts with remote guests or co-hosts over call apps such as Skype. Additionally, you can click the toggle switch next to the microphone to turn off your microphone audio.Setting up Skype for Wirecast use on Mac step by step: (and SoundFlowerBed with it). It's at the bottom of the video screen on the right.

SIP signalling and control traffic in Skype for Business takes the run of the mill approach вЂ“ traffic is routed directly between server and client. From the Audio Device settings, select.Audio and video establishment in Skype for Business takes a different approach to most network traffic. Go to Tools > Audio Device Settings or Video Device Settings.

For example, its the thing that tells the server you want to make a call by sending a SIP INVITE. SIP signalling вЂ“ simply put, itвЂ™s the control traffic. ICE is the overall process that helps discover and exchange вЂcandidatesвЂ™ 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 вЂ“ 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.

A home based user sends a packet to edge server, which discovers the public IP address (a candidate), and returns it to the client. Reflective/SessionВ Traversal Utilities for NAT (STUN) вЂ“ STUN вЂreflectsвЂ™ or returns the public NAT address to the Skype for Business client e.g. Candidates вЂ“ A list of possible IP addresses that could be used to establish an audio or video path.

With this, the client sends a SIP service request to the Front End server which includes the clientвЂ™s location (internal or external). The server provides a 200 OK which includes in-band provisioning details, including MRAS (audio or video relay authentication services) which tells the client there is an Edge server deployed. Edge server is doing STUN and TURN but not an ICE endpoint, and is more of an ICE server.The Skype for Business client does an SRV lookup to find an Edge server to register against and then performs a SIP register. Session Border controllers and the director role would not be considered as ICE endpoints. Skype for Business Clients, Skype for Business Web App, Skype for Business Phone, Front End Server (App Sharing MCU, RGS, Call Park A/V Conf etc), mediation Server, SBA, Exch UM. ICE endpoints вЂ“ An ICE endpoint is anything that is involved in audio or video e.g.

Host/Local Candidate (UDP) вЂ“ The most preferred candidate is always a local candidate and is the reason that peer to peer audio or video sessions between clients on the same network will never use the Edge server. If a better path is found the then audio or video path can change during the call: In a conferencing scenario the same thing happens, however, because of the possibility of joining a meeting anonymously, the Front End server checks to see if a meeting exists, and then gets and passes the credentials to the anonymous meeting participant.This is the process of determining the best possible candidate for the session. Credentials are valid for 8 hours, and for this period the client can now communicate directly with the Edge server. The AV Edge service creates credentials using the AV Edge certificate for the Front End server which sends a 200 OK back to client with the Edge server it should connect to, ports and username and password.

This connectivity is relayed through the public IP address of the Audio/Video Edge service. The calling client will establish an audio or video session directly with the A/V Edge Server as will the receiving client. Relay/TURN Candidate (UDP) вЂ“ In the event that STUN fails then the final option is to utilise the Edge Server as a media relay. The reflexive IPВ address is the public IP address of the external user e.g. This scenario involves attempting to connect to theВ reflexive IP addresses for each externally connected user.

In SIP 183 PeerВ sends its candidates. Candidates come in peers вЂ“ one for Real-time Transport Protocol (RTC) and one for RTP Control Protocol (RTCP).A=candidate 1 1 Protocol (UDP/TCP Passive вЂ“ candidate I expect to send traffic to /TCP Active вЂ“ candidate that sends me traffic) priority (high best) IPAddress Port Typ(host/relay/server reflective)A=candidate 1 2 UDP priority (high best) IPAddress Port Typ (host/relay/server reflective). OCS r2+ uses V19, but both are included for backward compatability. The first set of candidates is ICE v6 (ms-proxy-2007 fallback) and a second set is ICE V19. Out INVITE (SDP session description protocol вЂ“ tells the other party what I can do e.g. TCP Relay is a last resort.

Check logs for STUN and TURN candidates. Check if the Front End server can telnet to the FQDN on Edge server internal NIC. Get client logs from a fresh sign-in вЂ“ is there MRAS? If no, it canвЂ™t talk to the Edge server. Get Snooper installed to make reviewing the client and server logs easier.

I've been trying to get a handle on the entire process as we have deployed Lync 2013 in our environment (without enterprise voice), One question I can't seem to find an answer on is, what path does an external client that is using Lync Web App take when connecting to a conference for desktop sharing. The final re-invite will include this, but the result may not be in logs for a few seconds after connection.You are now ready to troubleshoot Skype for Business audio not working!Hopefully, you found this article useful and next time you have a Skype for Business audio not working issue youвЂ™ll have some new tools to help you.Thanks to Thomas Binder for thisВ excellent deep dive as well as Jeff SchertzВ for his summary.Good summary. After a call is picked up, it can take several seconds before the final candidates are chosen and audio or video paths are subject to change. Search a=remote-candidate to find the final candidates that are chosen Search client and server logs for a=candidate to find candidate information When the Edge server sends candidates in a NAT situation, it uses the external IP configured in topology and sends this to client вЂ“ make sure itвЂ™s correct!

With an internal full lync client user and an external lwa user scenario, I see the internal user candidate list look correct. This traffic will all drop because I was under the impression that communication with the front end servers or internal clients should go through the edge internal interface due to our persistent routes on edge.I started exploring the log files and candidate lists. I see the external edge ip trying to talk to the front end server ip on 3478 stun and occasionally other 50,000 or higher ports, as well as the front end server trying to talk to the external edge ip in the 50,000 range. Looking at our firewall logs, I see dropped communication between our front end server ip's and the external edge nic ip's.

It also shows the relay address of the edge's external ip.Looking at the logs on the lwa client, I see a candidate list that looks correct for its local ip information, but I also see candidate lists show up which list the information for our front end server as well. What seems odd is that, the internal client then receives a SIP 200 OK with a candidate list, but the list is the local ip of the front end server's nics (both the ip of the default nic for communication and the ip of the nic used to connect to some back end storage for the lync file share). I also see the relay ip of the external edge ip in the list.

Turn On Mac Audio For Skype