Voice over Internet Protocol (VoIP) security guide

How to ensure your VoIP phone systems are secure.

Voice over Internet Protocol (VoIP) security guide

How to ensure your VoIP phone systems are secure.

Whatever size your business, security is crucial for keeping your business safe. VoIP presents new risks with security, but there are still ways to maximise your business’ security with VoIP over traditional handsets.

Security is an essential asset for any business. This guide is designed to help you get the most out of VoIP while still maximising your security. VoIP comes with a whole host of benefits, including security – however, this all comes down to managing your security well and making sure to account for the new risks that arise with using VoIP technologies.

Keep on reading to understand the cyber threats that persist and how to mitigate these going forwards.

Why is VoIP security important?

Security is fundamental to both business success and business compliance, and with a[VoIP phone system that’s now easier than ever.

Unlike legacy systems and traditional handsets, which are dependent on an office network security, VoIP is a flexible and dynamic offering that caters towards hybrid working. However, VoIP needs to be protected against cyber-threats and vigilant measures should be put in place to limit the likelihood of a hardware attack or a data breach.

While technology continues to develop and advance around us, so too do the cyber-threats we come up against. As a business, it’s important not to bury your head in the sand, but rather get ahead of the curve and make sure that comprehensive cyber-security measures are in place. That’s where VoIP comes in. Now more than ever, it’s important to ensure that all calls are secure, whether that’s in the office or off-site. 

What are VoIPs main cyber security threats?

Common security threats that arise with VoIP are: call interception, ID spoofing and Denial-of-Service (DoS) attacks. There is also the risk of malware attacks, which previously were not a threat to traditional handsets. However, all of these VoIP security threats are manageable, provided businesses take the necessary precautions and make sure to be vigilant when transitioning to a VoIP system.


VoIP is just one of many Unified Communications solutions exposed to the threat of malware. The original malware, WannaCrypt, and all of its derivatives, have posed a significant threat to telephone systems and computer systems, with ransomware attacks taking out all communications systems to do maximum damage during cyber-attacks.

The crucial thing about malware attacks and VoIP security is that the threat itself does not come from the telephone system, but rather from a user opening a corrupted email on any device that is linked to the same channel as your Unified Communications solution. Therefore, with extra vigilance and awareness, businesses can make sure that they minimise this risk as much as possible.

Denial-of-Service (DoS) attacks

DoS attacks are designed to shut down a machine or network, resulting in it no longer being accessible to its users. DoS attacks are carried out by flooding a desired target with traffic or overloading it with information to trigger a crash. DoS attacks deprive users of the service they require, which often creates a ripple effect into wider company operations.

In the case of VoIP, cyber-criminals could try and shut down your business operations by sending your VoIP system high concentrations of information (such as spamming phone calls), which can trigger a wider system crash.

It is easy to protect your system against DoS attacks provided you keep your eyes open and try not to treat the threat in a similar way to what you would expect from other IT systems. Phone lines do not have the protection of firewalls or other cyber-security solutions, and so instil alternative security protocols within your directory information. By simply installing these, your business phone systemcan identify, reroute and filter calls coming from attackers.

Phishing scams

In some cases, VoIP’s are targeted by so-called ‘vishing scams’: instances when scammers contact users on numbers that are similar to those of a legitimate organisation and leave a message about suspicious activity occurring across a recipient‘s accounts (these might include banks, government agencies or tax authorities). The victim is then taken onto a separate call, where they are asked to verify their identity and hand over confidential details.

These scams can be avoided by familiarising employees with typical scamming tricks and by making sure that any scam numbers are flagged by your VoIP phone system and blocked.

Call tampering

VoIP systems can be vulnerable to call tampering as hackers try to disrupt your live calls. The effects of tampering can ruin the quality of calls or cause long delays and periods of silence while they try and share substantial amounts of data over the line.

Voice over Misconfigured Internet Telephones (VOMIT)

Using a VOMIT tool, cyber-criminals can steal voice snippets and confidential and sensitive information directly from your business calls. This threat can be dangerous, as criminals are also able to gain access to other information like the original call location, which can make it easier for them to eavesdrop on future calls and other communications.

However, with a[cloud-based VoIP provider, it is very easy to prevent VOMIT from being a threat to your business operations, allowing businesses to secure all of your data and sensitive information from criminals. 

As a business, it’s important not to bury your head in the sand, but rather get ahead of the curve and make sure that comprehensive cyber security measures are in place.

What can secure VoIP systems?

VoIP systems are without doubt more secure than traditional telephonE systems. Session Initiation Protocol (SIP) enables VoIP to provide a significantly more advanced and secure solution than was ever available through the Public Switched Telephone Network (PSTN) and Private Branch Exchange (PBX).

SIP is a signalling protocol for safe and reliable internet telephony. Using a SIP server allows voice traffic to be compressed into media streams, which are then sent over an internet connection rather than through traditional phone lines.

The primary reason that VoIP systems can be more secure than traditional networks is that these phones and their identities exist virtually. Users have access to their phones wherever they are, regardless of whether they are in the office or on the go, where previously there has been a heavy reliance on a central office phone system.

BT VoIP security

All of this is made possible because of cloud-based VoIP centres, which are connected to the internet through a network switch and linked into offices to enable communications. The data centres where we host our VoIP phone systems undergo robust audits. It’s why they have everything from firewalls to intrusion detection systems, and it’s why all of your data is encrypted – to protect it from cyber-attacks and unauthorised access. These VoIP phone security measures ensure that your business has the most comprehensive protection from potential threats.

How can you make your VoIP more secure?

While a VoIP phone system is already a significant security upgrade to a traditional communication system, there are ways to make it even more secure. These include but are not limited to:

  • encryption
  • network tests
  • VPN.


Using encryption allows you to protect your data even further. This way, even if it is intercepted or targeted by hackers, they will not be able to leak any valuable information as it is too difficult to decode.

Your information can be encrypted in multiple places to maximise the degree of protection even further, as well as encrypting the VoIP site itself. This prevents any real damage evolving from call tampering and criminal eavesdropping.

VoIP encryption is carried out by using the Secure Real-time Transport Protocol (SRTP), and then generating Advanced Encryption Standards (AES). There is also the additional option to use Transport Layer Security (TLS) to make sure that your business has covered all of its bases and has minimal exposure to tampering.

Network tests

They say that practice makes perfect, and that’s also the case for your network. Carrying out regular penetration tests and assessments to make sure that your network is safe against hacks by running simulations within your team is another avenue to alleviate threats such as malware attacks.

What’s more, in running these tests you can identify your weak spots and address them, which means that you are constantly being vigilant and evolving your own cyber-security precautions.


A VPN is an additional tool to have within your security artillery. It’s a great way of securing the data your business is transmitting over the internet. A VPN ultimately acts as an internal network, as it creates its own private network over which data can safely and securely be sent.

Choosing to set up a VoIP over a VPN helps to secure the SIP. It can do this by making a private and secure portal opening which is almost untraceable, limiting the threat of a hack or a data leak as the data is so difficult to pin down in the first place.

Cyber-security and remote working

Now, more than ever, it’s imperative that cyber-security is at the top of the agenda. Hybrid working has accelerated our reliance upon technology, which is why the introduction of secure solutions – such as VoIP – are so important right now. As a result, businesses need to make sure they have the infrastructure and solutions in place to minimise any cyber-threats.

The stronger your VoIP security solution, the stronger a position you put your business in as you are decreasing your exposure to threats that can ultimately cost you time and money.

Take the time to produce a cyber-security plan. Think about the solutions you need to support your cyber-security needs and how to create the smoothest transitions from a legacy phone system to VoIP.

Are you looking for a VoIP system with a trusted provider? With [BT’s VoIP phone system, you can stay connected while being assured that security is our priority.