Portal login
Talk to us Get started

Enhanced security

Security that never sleeps

Peak performance

Performance that scales with you

Zero downtime

Because that’s what matters

Multi-site resilience

True high-availability and failover, made easy

Industry solutions

Expertise in healthcare, object storage, and mission critical industries

Application solutions

Every application, documented with care

Partner solutions

Professional services

The ADC Portal

Any load balancer, anywhere, one simple platform

The Enterprise ADC

Smart, flexible, unbreakable — and trusted

Flexible licensing

No hidden costs,  no end of life — just great value

Get a quote

Get technical support

Reviews

based on 1,500+ reviews

Customer stories

Blog

Events

Not your average Load balancer company

Learn why we are different

How application delivery helps avoid travel disruption

Application Delivery Controllers help get me from A to B without incident in so many ways.
Get started

Load balancing Skype for Business

Updated on April 2, 2025
•
Published on March 8, 2023

About Skype for Business

Skype for Business is a business class instant messaging, voice over IP (VoIP) and video collaboration tool by Microsoft. Since 2015, it has served as a replacement for Microsoft Lync (formerly Microsoft Office Communications Server).

Unlike the consumer version of Skype, the infrastructure for is hosted on Skype for Business Server. This is comprised a number of individual servers including, Frontend/Backend, Mediation, Director and Edge servers. Due to the number of servers and services provisioned, there is inherent complexity in the deployment. This requires a considered approach to high availability and distribution of user traffic.

Key benefits of load balancing

Here are a few key benefits:

  • Ensures the application is always available
  • Provides a stable, optimal performance
  • Feature-rich highly resilient solution
  • Scalability

Microsoft’s Enterprise solutions are at the heart of businesses everywhere. Loadbalancer.org is officially certified for all of Microsoft’s key applications which you can find here. More details on the Skype for Business components, how it works, and prerequisites for load balancing can be found in our deployment guide, available to view below.

Deploying Skype for Business with Loadbalancer.org appliances enables organizations to create a feature-rich highly resilient solution that ensures that wherever staff are located, and however they connect, they can depend on a platform that allows seamless communications wherever and whenever needed using the communications medium of their choice.

How to load balance Skype for Business

Loadbalancer.org appliances are configured to present a series of Virtual Servers (VIPs). These VIPs become the connection points for internal and external clients. The load balancer is then able to distribute requests to the Skype for Business servers that make up the various pools.

Here’s an example deployment architecture:

Example fully balanced deployment utilizing 2 HA pairs. HA pair 1 is used to load balance the external Edge, HA pair 2 is used to load balance the internal Edge and all other roles.

Direct Routing (DR) mode a.k.a. Direct Server Return (DSR) mode is not supported for Skype for Business.

UDP traffic must be configured with Layer 4 NAT mode.

TCP traffic can use either Layer 7 SNAT (Reverse Proxy) or layer 4 NAT.

Front End Servers Protocols Table

Protocol Role Ports Load balancing methods
TCP/HTTP Internal Web Services Internal Web Services Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/DCOM/RPC Various DCOM based operations 135 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/HTTPS Internal Web ServicesUsed for HTTPS communication between the Focus (the Skype forBusiness Server component that manages conference state) and theindividual servers. 443,444 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/TURN Used for call admission control by the Skype for Business ServerBandwidth Policy Service 448 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/TLS/MTLS/SIP Various SIP based communication 5061 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/SIP/TLS Used by the Mediation Server for incoming requests from the Front EndServer to the Mediation Server 5070 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/SIP/MTLS Used for incoming SIP requests for the Response Group application, Attendant (dial in conferencing), the Skype for Business Server Conferencing Announcement service (that is, for dial-in conferencing), the Call Park application 5071, 5072, 5073, 5075 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/SIP Used for incoming SIP requests for the Audio Test service 5076 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP Used for call admission control by the Bandwidth Policy service for A/VEdge TURN traffic 5080 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/HTTPS External Web Services – from Reverse Proxy 4443 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/HTTPS External Web Services – from Reverse Proxy 8080 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)

Director Servers Protocols Table

Protocol Role Ports Load balancing methods
TCP/HTTPS Internal Web Services 443 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/HTTPS Inter-server communication between Front End and Director 444 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/TLS/MTLS/SIP Internal SIP communications between servers and for client connections 5061 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/HTTP External Web Services – from Reverse Proxy 4443 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)
TCP/HTTP External Web Services – from Reverse Proxy 8080 Layer 7 SNAT – (Flexible, Source IP and cookie insertion capabilities)

Edge Servers (External Interface) – Access (SIP) Service Protocols Table

Protocol Role Ports Load balancing methods
TCP/STUN Audio/Visual service 443 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)
UDP/STUN Audio/Visual service 3478 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)
TCP/MTLS/SIP Access (SIP proxy) service 5061 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)
TCP/MTLS/SIP Audio/Visual authentication service 5062 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)

Edge Servers (External Interface) – Access (SIP) Service Protocols Table

Protocol Role Ports Load balancing methods
TCP/TLS/STUN/SIP Access (SIP proxy) service 443 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)
TCP/MTLS/SIP Access (SIP proxy) service 5061 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)
TCP/XMPP Access (XMPP Proxy) service 5269 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)

Web conference service Protocols Table

Protocol Role Ports Load balancing methods
TCP/TLS/STUN/SIP Web conferencing 443 Layer 7 SNAT – (Source IP persistence)

Audio/Visual Service Protocols Table

Protocol Role Ports Load balancing methods
TCP/TLS/STUN/SIP Access (SIP proxy), Web Conferencing, Audio/Visual services 443 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)
UDP/STUN Audio/Visual service 3478 Layer 4 NAT – (Fast Load balancing throughput Source IP persistence)Layer 7 SNAT – (Flexible, Source IP persistence)

Get Started Today, for Free

Try us out — no strings, no stress, just seriously good load balancers and top-notch support.

Try for free Book a meeting