SIP Trunk Security: How Private Are Your Calls?

With VoIP and internet based telephony becoming the norm in business communications, the question of SIP trunk security and its effectiveness has become an important one.

Securing your data and making sure you’re reducing the risk of it being compromised has become a standard practice for even the smallest of businesses. With regulations like the GDPR (an ever-looming presence these days), it’s no wonder people have compliance and security in mind.

That being said, how important is the security of your voice traffic? Well if you’re a business that takes sales calls, conducts meetings, or exchanges customer information over the phone, you need to consider securing your comms.

SIP Trunks

The world of telecoms is evolving all the time, with better standard tech and cost savings. SIP trunks are swiftly becoming the industry standard for business voice traffic, with reduced costs and increased connectivity compared to the standard copper lines of the PRI ISDN.

New to SIP trunks? Take a look at our latest guide.

Basically, they’re used to transfer your call data through lots of different mediums, including private data networks and the internet – in a signal that can be easily converted for transmission across the plain old telephone system.

Protecting Your Data

Our favorite analogy is a highway. With your data as a car on the highway and the highway as a SIP trunk. When you go from one city to another (or in this case, between you and whoever you’re talking to) you use the highway to get there effectively, quickly and reliably.

But the highway is a public place. Would you risk walking down the street with all your private information on you? Probably not. And when you’re dealing with the public internet, you’re going to need a bit of security.

So when it comes to SIP trunking there are a number of security layers:

Secure Real-time Transport Protocol (SRTP)

So if you want to protect a car, what’s the first layer of protection you can have. Locking your car? Maybe even get a more difficult car to break into?

Either way, this is basically what you do when your data is transferred with Secure Real-time Transport Protocol.

It protects the contents of your car, in this case, the actual voice signal of the call. A bit like those fancy cars with the tinted windows.

Transport Layer Security (TLS)

Transport Layer Security is like disabling your cars GPS tracker. You don’t know where the car has come from or where it’s going. Although the call event and metadata isn’t as sensitive as the call itself, it’s still important info that a lot of people would rather be kept private. A good example is things such as DTMF tones that might be required by a bank asking an end user to verify their account details.

Virtual Private Network (VPN)

To protect and encrypt the route through which the call travels over any public networks

A VPN is the equivalent of having tinted windows, it costs a good bit of extra cash, but it keeps your data away from prying eyes and provides an extra layer of security.


For even greater security, the best bet is to avoid public networks (or roads in the case of our analogy) altogether with a dedicated interconnect to your supplier.

This is like having your own a private road with a big “No Trespassing” sign on it that the public is not allowed to use.


There are very real considerations around information security that companies need to keep top of mind. First and foremost, calls and call patterns should be fully secure and not logged anywhere external to your own platform or–and only if required–the platform of your communications provider.

When you choose a provider, make sure to check that they comply with any data security and privacy regulations in your industry or in the countries where you do business including the handling of sensitive data.

All in all, when it comes to securing your call data, a SIP trunk can give you total privacy, save you money, and provide access to a large customer base.

Are you looking to use SIP trunks for your business?

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