A
session border controller (SBC) is a piece of
network equipment or a collection of functions that
control real-time session traffic at the signaling,
call control, and
packet layers as they cross a notional packet-to-packet network border
between networks or between network segments. SBCs are critical to the
deployment of
VoIP networks, because they address the
inability of real-time session traffic to cross network address translation (
NAT)
device or
firewall boundaries.
[Source:
Heavy Reading - VOIP Session Border Controls]
