Creating Bypass IDs

All Lync network sites have a Bypass ID parameter assigned that is used to determine whether a client can use Media Bypass between itself and a trunk. This determination is based on comparing the Bypass ID of the trunk with the Bypass ID of the Lync endpoint.

In a new environment all network sites share the same Bypass ID, which means Media Bypass can be used between any site. After a site has a bandwidth policy applied, it is assigned a unique Bypass ID, but the other sites all retain the same, shared Bypass ID.

Media Bypass is blocked only if there is a bandwidth constraint between the two sites, so to prevent Media Bypass from being used between two sites, an administrator must associate a bandwidth policy to either network site. The actual values of the bandwidth policy don’t matter, but as long as a bandwidth policy is applied, a unique Bypass ID is generated for the site.

If the Bypass IDs of the client and trunk match, Media Bypass can be used. If they are different, Lync assumes that there is bandwidth constraint between the sites and will not use Media Bypass for the call to help preserve bandwidth.