VoIP Security Checklist for UK Businesses Quick Answer
Business VoIP can be secure, but it should be protected like any other cloud-based business system.
The most important controls are:
strong unique passwords
multi-factor authentication
encrypted signalling and voice traffic
restricted admin access
fraud monitoring and outbound call limits
patched phones, apps and network equipment
secure call-recording storage
controlled access for remote workers
provider resilience and incident-response processes
If you’re comparing phone systems rather than reviewing security controls, see our Business VoIP Phone Systems UK guide.
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Authored by: Ally Cox (Business Technology & B2B Services Specialist 10+ Years’ Experience)
Reviewed by: James Ward (Telecoms Specialist, 12+ Years Experience)
Last Updated: October 2026
Key Takeaways
VoIP security starts with identity, access and fraud controls.
MFA should be enabled for admin and user accounts wherever supported.
Default passwords and shared admin accounts should be avoided.
TLS can protect signalling while SRTP protects real-time voice media.
International and premium-rate calling should be restricted where it is not needed.
Call recordings may contain personal data and should have clear access and retention controls.
Remote workers need approved apps and secure device policies.
VoIP providers should be assessed for resilience, support and incident response as well as price.
VoIP Security Checklist
Security control What to check Why it matters
MFA
Admin and user accounts support multi-factor authentication
Reduces account-takeover risk
Passwords
No default/shared passwords; strong unique credentials
Protects user and administrator accounts
Encryption
TLS/SRTP or equivalent protection
Protects signalling and call media
Admin access
Role-based permissions and limited administrator accounts
Reduces unnecessary privileged access
Fraud controls
Call barring, spend limits and unusual-call alerts
Reduces toll-fraud exposure
Patching
Phones, apps, routers and PBX software kept up to date
Fixes known vulnerabilities
Remote access
Approved apps, MFA and device controls
Protects home and mobile workers
Call recordings
Access, encryption, retention and deletion controls
Protects personal and sensitive information
Provider resilience
Monitoring, DDoS controls, recovery and support process
Reduces disruption risk
Incident response
Clear internal and provider escalation process
Helps contain fraud, outages and account compromise
What Are the Main VoIP Security Risks? The main risks for a business VoIP system include:
Risk What it means
Account takeover
An attacker gains access to a user or administrator account
Toll fraud
Unauthorised calls are made through your system
Call interception
Voice or signalling traffic is accessed without permission
Weak admin controls
Too many users have high-level permissions
Unpatched devices
Old software or firmware exposes known vulnerabilities
Insecure remote access
Employees connect through unmanaged devices or weak authentication
Recording exposure
Stored call recordings are accessed or shared incorrectly
DDoS/service disruption
The phone service becomes unavailable or degraded
Social engineering
Attackers use calls to impersonate staff, suppliers or banks
1. Enable Multi-Factor Authentication MFA is one of the most important controls for cloud VoIP., and you should use it for:
administrator accounts
user portals
softphone accounts
Microsoft 365 accounts
billing portals
support portals
If your provider does not support MFA for sensitive administrative access, that should be a major consideration when comparing alternatives.
2. Remove Default and Shared Passwords Default credentials should be changed immediately – use:
unique passwords
separate administrator accounts
a business password manager
regular access reviews
3. Use Encryption for Signalling and Voice Ask what parts of the VoIP service are encrypted.
Common protocols include:
TLS for signallingSRTP for real-time mediaHTTPS for web administration
For example, Microsoft says Teams uses TLS for signalling and SRTP for audio and video media.
Do not assume that every VoIP platform provides true end-to-end encryption for every type of call. Microsoft, for example, offers optional end-to-end encryption for supported one-to-one Teams calls, while standard Teams communications use TLS and SRTP.
4. Restrict Administrator Access Administrator accounts can change:
users
numbers
call routing
voicemail
recordings
billing
integrations
Use:
least-privilege access
role-based permissions
named administrator accounts
regular permission reviews
audit logs where available
5. Protect Against VoIP Toll Fraud Toll fraud happens when an attacker uses a compromised phone system to make unauthorised calls.
Useful controls include:
international call blocking
premium-rate blocking
user-level call permissions
spend limits
unusual-call alerts
out-of-hours restrictions
provider fraud monitoring
6. Secure SIP and Network Access Hosted and on-premise PBX systems should not expose unnecessary network services, ,and depending on the deployment, this can include:
restricting SIP access
closing unnecessary ports
separating guest Wi-Fi
using appropriate firewall rules
monitoring suspicious traffic
Detailed implementation should follow your provider’s or network specialist’s configuration guidance rather than generic port rules copied from another platform.
7. Keep Phones, Apps and Network Equipment Updated Review security updates for:
VoIP desk phones
softphone apps
mobile apps
routers
firewalls
PBX software
operating systems
Teams or other collaboration apps
The key principle is to follow vendor-supported versions and install relevant security updates promptly rather than using an arbitrary monthly or quarterly schedule for every product.
8. Protect Remote Workers Remote users introduce additional devices and networks that the business may not fully control, so make sure you ue:
approved VoIP applications
MFA
screen locks
supported devices
up-to-date software
quick access removal when staff leave
If employees use personal devices, your device policy becomes particularly important. See our BYOD policy and security guide rather than duplicating device-management controls here.
9. Secure Call Recordings Call recording is a data-protection issue as well as a VoIP feature.
Recordings may contain information about customers, employees or other identifiable individuals.
Control:
who can access recordings
why calls are recorded
how long recordings are retained
whether recordings can be downloaded
how recordings are deleted
where recordings are stored
how access is logged
10. Have a Clear Recording Retention Policy There is no single universal retention period for every business, the better approach is:
define why recordings are required
identify how long they are genuinely needed
document that retention period
delete recordings when the purpose no longer applies
11. Protect Voicemail and Call Forwarding Voicemail and forwarding settings can be overlooked, so always check:
default voicemail PINs have been changed
old mailboxes are removed
call-forwarding changes are controlled
international forwarding is restricted where unnecessary
shared voicemail access is reviewed
12. Train Employees Against Vishing Vishing is voice-based social engineering.
Employees should be cautious when callers:
request passwords
ask for payment changes
claim to be IT support
impersonate suppliers or banks
create artificial urgency
ask staff to bypass normal verification
Technology cannot prevent every social-engineering attack, so verification procedures and staff awareness remain important.
13. Plan for VoIP Outages and Security Incidents Your incident plan should cover what happens if:
administrator credentials are compromised
fraudulent calling is detected
calls are being redirected
the provider has an outage
recordings are exposed
a remote device is lost
customers cannot reach you
Record:
provider emergency contacts
internal decision owners
backup numbers
call-forwarding options
credential reset procedures
fraud-response steps
incident logging
Does VoIP Need DDoS Protection? Businesses that depend heavily on phone availability should ask their provider how it handles denial-of-service attacks and wider service disruption. We’ve written about DDoS in depth here .
Ask:
how the provider monitors attacks
what mitigation is in place
how resilient the platform is
what support route applies during incidents
what service commitments are included
Is Microsoft Teams Phone Secure? Microsoft Teams uses several layers of security for calling and collaboration.
Microsoft currently documents:
TLS for signalling
SRTP for media
Microsoft Entra ID for identity
OAuth-based authentication
encryption of Teams data in transit and at rest
If Microsoft is your main buying intent, see our dedicated Microsoft Teams Phone guide .
VoIP Security and BYOD If staff use personal phones or laptops, security controls should focus on the business applications and data rather than simply assuming the personal device is trusted.
This can include:
approved work apps
MFA
minimum device standards
business/personal data separation
access revocation
See our dedicated BYOD guide for device-management detail.
What Should You Ask a VoIP Provider About Security? Before signing, ask:
Is MFA available for users and administrators?
How are signalling and voice traffic encrypted?
Can international and premium-rate calls be blocked?
Do you monitor for unusual or fraudulent calling?
Can administrators use role-based permissions?
What audit logs are available?
How are recordings encrypted and stored?
Can we control recording retention?
How do you protect the platform from service disruption?
What happens if an account is compromised?
How quickly can users be disabled?
What incident-response support is available?
What data-processing terms apply?
How is number porting protected?
If a provider cannot explain these controls clearly, include that in your comparison.
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Does Secure VoIP Cost More? Basic security should not be treated as a premium luxury.
Controls such as strong authentication, encrypted applications, secure administration and fraud monitoring should be expected from a credible business communications service.
Costs can often rise where you require additional services such as:
advanced compliance recording
long-term recording storage
specialist audit tools
contact-centre security features
enhanced support
complex private connectivity
Do not create a separate “secure VoIP price” budget. Instead, compare whether the security controls you actually need are included in each proposed phone-system package.
Our Verdict: Is Business VoIP Secure? Yes, business VoIP can be secure when identity, network, device and provider controls are configured properly, and your highest-priority checks are:
MFA
strong unique passwords
encryption
restricted administrator access
toll-fraud controls
patching
secure recordings
remote-user controls
provider resilience
If security is one of several factors you are using to choose a new platform, compare systems through our business VoIP phone systems pillar or business VoIP provider comparison .
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Frequently Asked Questions Is VoIP secure?
Yes, VoIP can be secure when it uses strong authentication, encryption, restricted administration, current software and appropriate provider security controls.
Can business VoIP be hacked?
Yes. Internet-connected phone systems can be compromised if passwords, SIP services, admin portals or network controls are poorly secured.
What is the biggest VoIP security risk?
There is no single risk for every organisation, but compromised credentials and weak administrative controls can create significant exposure because attackers may gain access to call routing, accounts and billing.
What is VoIP toll fraud?
Toll fraud is unauthorised use of a phone system to make chargeable calls, often to international or premium-rate destinations.
How do I prevent VoIP toll fraud?
Use MFA, strong passwords, call barring, spend limits, destination restrictions, unusual-call alerts and provider fraud monitoring.
What is TLS in VoIP?
TLS is commonly used to encrypt signalling used to establish and manage VoIP sessions.
What is SRTP?
Secure Real-Time Transport Protocol is used to protect real-time audio or video media in supported communications systems.
Does VoIP need a VPN?
Not always. A modern cloud VoIP application may provide encrypted communication without requiring a VPN. Whether a VPN is appropriate depends on the provider, network design and security policy.
Are VoIP call recordings personal data?
They can be if they contain information relating to identifiable people. Businesses should control why recordings are made, who can access them and how long they are retained.
How long should call recordings be kept?
There is no universal period. Set a retention period based on the purpose for recording and delete data when it is no longer needed.
Is Microsoft Teams Phone secure?
Microsoft documents TLS, SRTP, Entra ID authentication and encryption at rest and in transit as part of the Teams security architecture.
Should small businesses use MFA for VoIP?
Yes. MFA is particularly important for administrator accounts and should also be enabled for users where supported.
What should I look for in a secure VoIP provider?
Look for MFA, encryption, role-based admin controls, fraud monitoring, call restrictions, secure recording, strong incident support and clear resilience arrangements.
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Hi, I’m Ally Cox , a senior copywriter and blogger at CompareYourBusinessCosts.co.uk, the UK’s trusted platform for comparing business services.over a decade of experience in the B2B sector, I specialise in simplifying complex topics like leased lines, VoIP, business energy, HR and payroll solutions, accounting software, and EPOS systems .HR, copywriting, and business operations- from clocking-in systems to card machines and office technology .informed, confident decisions when choosing products and services that improve efficiency and save money.
