Topic Last Modified: 2010-11-04

When you enable media bypass, a unique bypass ID is automatically generated for a network region and for all network sites without bandwidth constraints within that region. Sites with bandwidth constraints within the region and sites connected to the region over WAN links with bandwidth constraints are each assigned their own unique bypass IDs.

When a user makes a call to the PSTN, the Mediation Server compares the bypass ID of the client subnet with the bypass ID of the gateway subnet. If the two bypass IDs match, media bypass is used for the call. If the bypass IDs do not match, media for the call must flow through the Mediation Server.

When a user receives a call from the PSTN, the user’s client compares its bypass ID to that of the PSTN gateway. If the two bypass IDs match, media flows directly from the gateway to the client, bypassing the Mediation Server.

In Lync Server 2010, only Lync 2010 clients and devices support media bypass interactions with a Lync Server 2010 Mediation Server.

If you want to force bypass in certain cases, you can use Windows PowerShell cmdlets to overwrite automatically assigned bypass IDs. The need to do this, however, should be very rare.

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