Why VoIP Solution Providers Must Have Session Border Controller in their VoIP Network

Regardless of pandemics or recession there is one business segment that will always thrive and that is communication. Today it is VoIP all the way and the emerging 5G will make it even more solidly entrenched. VoIP service providers get started with class 4/5 softswitches and assume that they have all that is needed. It works most of the time but then complaints start pouring in about calls not going through and poor audio quality. That is the least of their worries. Should a DoS or DDoS attack take place they are up the proverbial creek without a paddle. It is assumed that the carrier with whom they have a tie up has a session border controller so why should they invest in one when they have a firewall. Dear VoIP service provider, you need an SBC solution and for all the right reasons. You do not want your customers to leave do you? Read on.

Correcting SIP flaws

You cannot do without SIP but it has flaws. One is the issue of network address translation or NAT traversal. SIP does not work if users are behind NAT.

  • SIP come in different flavors and that can pose issues of interoperability. This is taken care of by the SBC that handles all SIP variations SBC solutions from top vendors take care of this basic roadblock on the highway of VoIP traffic.
  • Service providers no longer face the issues of dropped calls or calls not connecting.
  • Then, the SBC also serves another vital function as a B2BUA, working as a user agent server for the caller and the user agent client for the callee and terminating the call.
  • With the SBC in place SIP can be transported over SCTP, TCP and UDP over IPv4/IPv6.


As a VoIP service provider you probably have hundreds of business customers. Each one has an internal network in place. Throw VoIP into the works and the topology problem rears its ugly head. It has to do with SIP and the way it opens up and exposes internal ports. Any hacker could get to know the internal addresses and worm his way in with disastrous results for that company’s data. A hacker could just as well cloak himself and use the network to make unauthorized calls. Your client is saddled with bills for calls they did not make and you may have to bear the cost. Put a SBC solution in place. It hides all internal network topology and presents an “inscrutable” face to the external network. People with malintent are flummoxed and your clients as well as they networks stay safe.


Security is number one reason to use session border controller. VoIP networks are increasingly under attack by hackers and are not fully secured by firewalls. Your network or a user network could be the victim of a denial of service or distributed denial of service attack. In this case the entire network is jammed and nothing goes through or comes in. A hacker could burrow in and steal data. He could use the services for free. People with malicious intentions could eavesdrop or catch packets. The session border controller includes strong security protocols that identify when a DoS attack is underway and closes the network if traffic exceeds limits. It will detect attempts at intrusion or injection and it will encrypt packets to prevent their being read. It has dynamic blacklisting feature. SBC keeps your network secure and operational so that your customers do not face issues of logjam.

Media codec transcoding

Today’s VoIP networks carry signals based on a variety of audio and video codecs plus mobile codecs. If there is codec mismatch or if the system is not able to transcode media codecs then the call does not go through or parties cannot hear each other. The session border controller includes packet service profile to allow codecs, decide packetization parameters, handle modems and DTMF, and transcode combinations. It works seamlessly in the background and users never have to worry about audio clarity or being able to view videos. WebRTC is one such recent addition to the codec family and were it not for the humble SBC it is doubtful if many people would be able to enjoy its use.


The SBC does more. It handles routing. Least cost routing is one of the best known examples of routing. If you have an intelligent LCR it will pick the first available lowest cost route and if it is not then the next, without appreciable delay. Going a step further the SBC also interacts with centralized PSX and/or local Policy Server to define and put in place calling and routing routes for subscriber and called party as well as trunk group. You will also appreciate that the SBC handles local number portability, digit manipulation and congestion control.

Think of the SBC as a watchdog. Think of it as a facilitator. Think of it as a cost controller. Think of it as your friend. Without it VoIP services would take a hit and your customers will not get the most out of VoIP. Do yourself a favor and do them a favor. Get SBC solution from a top vendor.

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