SBC Thoughts


I can remember the early 90s when the Firewall was born. There was so much confusion.

I can remember spending $20k (back then) on an enterprise firewall to protect our corporate citizens from the evils that lurk on the Internet. I can also remember when only a few special PCs in the office were allowed to connect to the Internet.

A lot has changed. Now Internet connectivity is a birth-right, and firewalls are much simpler than before. Some firewalls are effectively free, built into the base operation of a consumer class router. High end firewalls still exist, but we have a better understanding of what they do and when we need them.

SBCs are going through a similar adoption curve. SBCs are effectively firewalls for real time communications and there are a lot of different models to choose from. Firewalls weren’t designed to accommodate SBCs, so instead we poked holes in the firewalls and just said to pass the SIP traffic to some device like an IP PBX. This work initially because the traffic was new. Now, SIP traffic is more mainstream – and protection is necessary as evil SIP traffic exists. Like the firewall’s, some SBCs are becoming free – built into consumer grade devices. High-end SBCs also exist, and we are beginning to get a better idea of what they do and when we need them.

Turns out the core SBC function is only part of the equation. We also want them for logical edge services such as transcoding. They can play a  key role in disaster recovery and HA.

I find a lot of confusion remains around SBCs. You can learn more about them at this new TMC SBC page. Toward the bottom of that page,I contributed a white paper called the SBC Conundrum which continues this conversation – about what the issues are in selecting an SBC and what the common mistakes are in selecting the wrong one (hint: speeds and feeds are only part of the story). SBCs are probably the most misunderstood network device – and yet one of the most critical for secure and scalable real time communications.

Dave Michels