We use an on-premises Skype for Business Server VoIP service that utilizes the Kemp LoadMaster LM-2400 for service resiliency. This allows our three front-end servers to seamlessly support our service. We never miss a call and our chat service is always ready as a result.
Kemp has a pre-made virtual service profile that perfectly fits our use case so the initial setup is quite easy. We also have expanded the use of the LoadMaster to accommodate a number of ancillary services that also require resilience.