Media Bypass

Planning for Media Bypass is not too complicated because it encompasses only identifying which media gateways in the organization support the feature and then configuring the trunks appropriately to enable the support. The majority of the configuration typically involves defining the previously discussed network topology correctly. Media Bypass enables a Lync endpoint to communicate directly with a media gateway, bypassing the Mediation server role with the G.711 audio stream. Figure 32.10 displays how a user’s signaling traffic continues to flow through the server to the media gateway, but the actual audio stream is sent from the user directly to the media gateway.

Figure 32.10. Media Bypass.

Media Bypass is especially useful in branch office scenarios in which no Mediation server is present, but a local media gateway exists. Without Media Bypass, calls are sent across a WAN link to a Mediation server at the central site, transcoded to G.711, and then sent back across the WAN link to the media gateway. With Media Bypass, endpoints can send the G.711 audio directly to the media gateway without traversing the WAN.

Media Bypass can be enabled in two distinctly different modes. The first mode turns on bypass at all times, and although easy to configure, it can cause quality issues. The second, more preferred approach is to base Media Bypass decisions from the network configuration entered for Call Admission Control.