Today let’s talk about the SBC.

I’ve mentioned SBCs here in the past, on the Lync Add-On Hardware post last year.

A new prospect reminded me of the SBC, as their situation will require one for interoperability reasons. They have several different types of VoIP phones scattered between 3 locations.

(Disclaimer: PlanetMagpie is a Sonus Partner. We use their SBCs for Skype for Business deployments, as well as our own Skype4B server. They didn’t ask me to write this though!)

That said, the reminder spurred me to a thought. “Have I gone into detail on what an SBC does yet? No, I don’t think so. Well, that’s this week’s topic then.”

What’s an SBC?

SBC stands for Session Border Controller. It’s a discrete hardware device which sits in the edge network. There, it

looks at each SIP packet going between your Skype for Business Enterprise Voice network and the external ISP. It determines which packets should be allowed through, and which route they should take.

Server Rack

What Does an SBC Do?

SBCs provide multiple security and mediation services within a VoIP environment.

Let’s say you have two phones – one onsite in your network, one offsite. Bob at Offsite picks up the phone & calls Jane at Onsite. This VoIP call is called a “session”. The SBC looks at Bob’s incoming call, determines that it’s legitimate, and lets it through to Jane. Hence, “Session Border Controller”.

Taking on this role helps stop a lot of bad things from happening. Within a Skype for Business deployment, SBCs can:

  • Protect the network from Denial of Service attacks, spoofing, and other outside attacks
  • Enable SIP trunking
  • Support interoperability between different endpoints (e.g., different VoIP phone types, as I mentioned in the opening above)
  • ‘Transcoding’ calls – Changing the codec used in a call, depending on the session type (audio, video), device type (tablets, laptops, phones), and bandwidth available

Why Would I Need an SBC in my Skype for Business Deployment?

Does your network suffer break-in attempts or DoS attacks? The attackers will target your Skype for Business network too. No question. It needs protection. SBCs are good for that.

Do your people ever call out? There’s no guarantee the SIP endpoints (VoIP phones) will talk to one another. Each phone can have a different bit rate. And if they do, they can’t connect to one another properly. Unless you use an SBC to bridge them (a process called ‘transrating’).

These are the two biggest reasons for an SBC. More exist, depending on your network configuration & security.

Okay then, what SBC should I use?

Right now, according to the Telephony Infrastructure for Skype for Business page on Office TechCenter, only two session border controllers are certified for Skype4B use.

Oracle Net-Net 3820
Sonus SBC 2000

(The Lync Server 2013-approved SBCs will work too. Here’s the full list.)

The Sonus SBC 1000 will also work for Skype for Business; we’ve tested it and the 2000 in small business deployments. Both of them do the job nicely. For Lync Server, we have several 1000s running at customer sites.

You CAN run Skype for Business (or Lync Server) without a Session Border Controller. It’s not mandatory. But it is helpful.

Want more? Sonus has kindly published a simple guide on using SBCs.
Ebook – Session Border Controllers for Dummies

I also like the Skype for Business guide: Ebook – Skype for Business for Dummies.

Both provide good overall explanations for Skype for Business and SBCs.

Do you use a Session Border Controller in your Skype for Business Deployment? What was the primary reason? Please comment or email your thoughts.  And join us again next week!

The SBC and Its Role in Skype for Business
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