{"id":85212,"date":"2020-11-26T14:56:59","date_gmt":"2020-11-26T14:56:59","guid":{"rendered":"https:\/\/loopup.com\/?p=85212"},"modified":"2022-06-23T09:40:08","modified_gmt":"2022-06-23T08:40:08","slug":"what-is-a-session-border-controller-sbc-how-does-it-work","status":"publish","type":"post","link":"https:\/\/loopup.com\/us\/resource-center\/blog\/what-is-a-session-border-controller-sbc-how-does-it-work\/","title":{"rendered":"What is a Session Border Controller (SBC) & How Does it Work?"},"content":{"rendered":"\n

As cloud telephony<\/a> adoption continues to grow, many enterprises are moving towards unified communications (UC) platforms like Microsoft Teams<\/a>. Microsoft Teams has long been used for efficient communication and collaborations internally, but external voice calling is now possible as well.<\/p>\n\n\n\n

With Microsoft Calling Plans<\/strong> or Direct Routing<\/a> using a third-party managed service provider, organizations can provide both internal and external calling from any Teams-enabled device around the globe. Implementing Direct Routing, however, will require a properly configured Session Border Controller. <\/p>\n\n\n\n

With this in mind, let\u2019s take a closer look at what Session Border Controllers are and how they work in the context of cloud telephony and Microsoft Teams.<\/p>\n\n\n\n

What is a Session Border Controller?<\/h3>\n\n\n\n

Session Border Controllers (SBCs)<\/strong> are devices deployed at the border between private and public networks. For example, an SBC can securely and efficiently transfer data from Microsoft Phone System<\/a> \u2014 a hosted Private Branch Exchange (PBX) <\/strong>\u2014 to the PSTN network or aggregate of all global telephone networks. That\u2019s why SBCs are often referred to as PSTN Gateways<\/strong> as well.<\/p>\n\n\n\n

A communication<\/strong> session<\/strong> is a real-time stream of communication between two or more users, which could take the form of a voice call, video conference, or instant messaging. The session usually includes the call\u2019s audio or video data as well as other information related to the session, such as time and media descriptions. The SBC ensures this session data flows in the form of packets to the correct endpoint.<\/p>\n\n\n\n

In a MS Team Direct Routing implementation, the border<\/strong> is the edge where Microsoft Phone System connects to the PSTN network. The SBC needs to be properly configured to route outgoing calls to regional carriers and incoming calls to the correct Teams user. SBCs can handle the task of monitoring communication traffic and applying policies in real-time much better than conventional networking devices like routers, firewalls, and traffic shapers.<\/p>\n\n\n\n

Most SBCs today support the Session Initiation Protocol (SIP)<\/strong>, which Microsoft recently announced additional phone compatibility<\/a> for as well. SIP is an open signaling protocol that the SBC uses to establish, maintain, and terminate communication sessions between two endpoints. More specifically, SIP trunking<\/strong> is the method SBCs use for connecting Microsoft Phone System to the public network. For Direct Routing, however, organizations must use Microsoft-certified SBCs<\/a> from vendors like Ribbon or Audiocodes which have been thoroughly tested with the latest version of Microsoft\u2019s code.<\/p>\n\n\n\n