Cybersecurity Due Diligence Checklist for VoIP/SIP Providers

Australian businesses are seeing more cyberattacks hit their phones, not just their laptops and servers. As more teams move from old landlines to VoIP and SIP, your phone system now sits right beside your core IT systems in terms of risk and impact.

This checklist is here to help IT leaders, CISOs and business owners stress test a new VoIP or SIP provider before signing anything. We will walk through compliance, telecom cybersecurity controls, SLAs, incident response and data residency so your phones are ready before the next cyber storm hits.

Protect Your Phones Before the Next Cyber Storm Hits

When trading ramps up, your phones carry orders, bookings, support calls and payments. If that system goes down because of a cyber incident, the business does not just slow down, it can stop.

A compromised VoIP or SIP service can lead to:

• Lost sales during peak periods  
• Staff locked out of key lines and queues  
• Attackers listening to or redirecting calls  
• Data leakage that may trigger reportable breaches under the Privacy Act  

Phones are now mission critical, especially for contact centres, healthcare, finance and government. Treating them as a side project for IT is a fast way to get caught out when threats increase.

This checklist is about asking sharper questions so you can shortlist providers that support your security goals, not weaken them.

Map Your Compliance and Regulatory Risk First

Before you speak to vendors, be clear on what you must protect and which rules you must follow. Telecom cybersecurity should line up with the same standards that guide your other systems.

Start by mapping what applies to your organisation:

• Privacy Act and Australian Privacy Principles  
• ASD Essential Eight alignment or similar hardening strategies  
• Industry rules for health, finance, education or government  
• Internal governance policies for data, access and incident reporting  

Then ask potential providers:

• What formal audits or certifications do you hold, if any?  
• How do you handle, store and delete customer data?  
• What encryption do you support for signalling and media?  
• How do you manage passwords, roles and access to admin portals?  
• How will your platform support our existing compliance obligations?  

Bring your VoIP and SIP services into your risk register and business continuity plans. Phone outages, call fraud and exposure of recordings should sit alongside database and network risks, not in a separate bucket.

Scrutinise Security Controls and Telecom Infrastructure

Once you know your compliance needs, it is time to look under the hood. Ask providers to explain their telecom cybersecurity controls in plain language.

Key safeguards to check include:

• Network segmentation for voice and management traffic  
• SIP trunk security and rate limiting to block brute force attacks  
• DDoS protection around signalling and media  
• TLS and SRTP support for encrypted call set-up and audio  
• Multi-factor authentication for admin and portal access  
• Fraud detection for toll fraud and account takeover  

Infrastructure choices matter too.

• Use of Tier 1 carriers for stable call quality  
• Redundant data centres within Australia  
• Upstream security partners and scrubbing services  
• 24/7 monitoring and proactive alerting  

Ask for:

• A high-level architecture overview that your IT team can review  
• Summaries of recent penetration or security testing  
• Clear guidance on how their controls will work with your firewalls, SBCs and corporate network  

If a provider cannot explain their design in simple terms, that is a red flag for both security and support.

Demand Transparent SLAs and Incident Response Playbooks

Security is not just about tools, it is also about promises and process. Your SLA should talk about more than uptime.

Key SLA elements to nail down:

• Uptime targets and how they are measured  
• Jitter and latency thresholds for acceptable call quality  
• Time to respond to security alerts or tickets  
• Time to resolve for outages and confirmed incidents  
• Service credits or penalties if targets are missed  

Incident response should be just as clear. Ask for:

• Defined escalation paths and named roles  
• 24/7 channels for urgent security events  
• Joint incident runbooks that set who does what and when  
• Agreement to join post-incident reviews and share findings  

Early detection and fast, open communication can turn a bad day into a manageable one. Check:

• What telemetry and logs they can share with your team or SOC  
• How quickly they notify you about suspicious activity on your accounts  
• How they support your duties around mandatory breach notification  

Get Clarity on Data Residency, Sovereignty, and Privacy

Data residency is where your data is stored. Data sovereignty is which country’s laws apply. For Australian organisations, keeping VoIP and SIP data within Australian borders can reduce exposure to foreign rules.

Important questions to ask each provider:

• Where is signalling processed and stored?  
• Where is media, such as call audio, handled?  
• Are call recordings and logs kept only in Australian data centres?  
• Which third-party vendors or sub-processors can access our data?  
• How long are different types of data retained?  

These choices link directly to privacy and reputation. Many enterprise and government customers now ask detailed questions about where their calls travel and who can see related data. Your telephony decisions will shape how confident they feel in your security stance.

Put Vendors to the Test Before You Sign Anything

A smooth sales demo is not proof that a provider is ready for a real cyber event in the middle of your busiest week. Put structure around your decision.

Consider:

• A clear RFP or RFQ with security and compliance criteria  
• Detailed security questionnaires for shortlisted vendors  
• Reference checks with customers in similar industries  
• A proof-of-concept under real-world load and call flows  

Ask scenario-based questions such as:

• How have you handled a major outage or attack in the past?  
• What did you change afterward in your SLAs, monitoring or response?  
• How do you test your own disaster recovery plans?  

Also look beyond technology. In Australia, local support and shared mindset between your staff and the provider’s team can make all the difference when something unexpected hits.

Turn This Checklist Into Your VoIP Security Game Plan

To make this checklist practical, turn it into a scoring tool. Split your requirements into must-have and nice-to-have items, and create a simple comparison table across your final providers.

Bring in voices from:

• IT and network teams  
• Cybersecurity or risk staff  
• Legal and privacy advisors  
• Operations and contact centre leaders  

Set a regular review of your current VoIP and SIP services before high-pressure trading periods. That gives you time to tighten controls, improve monitoring and refine runbooks.

At NewVo, we focus on tailored business communication solutions for Australian organisations that want better, safer ways to connect with customers. When you are ready to review your telephony setup, a security-first conversation can often lift reliability, protection and customer experience all at once.

Protect Your Communications With Proven Security Expertise

If you are ready to tighten controls around your phone systems and keep sensitive conversations safe, we can help you put the right safeguards in place. Our telecom cyber security solutions are built to protect your business without disrupting how your team communicates. Talk with the NewVo team about your current setup and we will outline practical steps to reduce risk. To get started, simply contact us and we will walk you through your options.