Microsoft Skype for Business Location-Based Routing (LBR) is designed for a mediation pool that contains trunks from a single site. The May 2017 cumulative update for Skype for Business Server 2015 that contains LBR fixes enforced strict LBR checking. It's not supported to connect trunks from other sites (such as branch sites) to the LBR enabled central site mediation pool. This LBR requirement may conflict with other business requirements to provide branch site resiliency or high availability enterprise voice service. If a local survivable branch appliance or survivable branch server (SBA/SBS) fails, the users are registered against the central pool and the enterprise voice calls should be routed through the central mediation pool by using the backup trunk to egress to the local branch PSTN gateways. This update satisfies both LBR and branch site voice resiliency requirements.