How to Secure VoIP Calls Without an IT Team

Voice over Internet Protocol (VoIP) technology has revolutionized business communications, offering cost-effective and flexible alternatives to traditional phone systems. However, with this convenience comes significant security risks that small and medium businesses can’t afford to ignore.   

The stakes are higher than ever: According to the Federal Trade Commission (FTC), Americans aged 60 and older have lost more than $745 million to scams in the first three months of 2025, nearly $200 million more than at the same time last year.   

Many of these scams involve phone-based fraud that exploits vulnerabilities in communication systems. That’s why for SMBs and resellers operating without a dedicated IT team, securing VoIP calls is an ongoing necessity that might look overwhelming if you’re just getting started.   

But it should not. Implementing robust VoIP security doesn’t require extensive technical expertise, and with the right knowledge and tools, you can protect your business communications from eavesdropping, fraud, and cyberattacks while maintaining the cost benefits and flexibility.  

Why Securing VoIP Calls Should Be a Business Priority  

The harsh reality is that every day you delay implementing security, your business becomes a more attractive target for cybercriminals.   

The transition from traditional phone systems to VoIP brings undeniable advantages, but it also fundamentally changes your security landscape in ways that could cost your business.  

VoIP delivers flexibility, but also increases exposure  

While VoIP services gives you incredible flexibility, it also opens doors that criminals are already walking through.   

Traditional phone systems operates on dedicated circuits with built-in security through physical infrastructure. VoIP changes this equation entirely by transmitting voice as data packets over the internet, creating new vulnerability points that didn’t exist before.  

Key exposure points include:  

• Voice data travels across the same networks as your email and web browsing  

• Remote work capabilities expand your attack surface  

• Each device and application becomes a potential entry point  

Cyber threats are growing across small business networks  

Small and medium businesses face a perfect storm of increasing cyber threats and limited security resources. While large enterprises have dedicated security teams, SMBs often discover breaches only when the damage is already done.   

According to Qualysec, nearly half (43%) of all cyberattacks specifically target small businesses. Attackers see it as easy pickings because of their limited security resources and infrastructure gaps.   

Most SMBs can’t afford enterprise-grade security tools or dedicated IT security staff. The result is clear: Weaker defenses mean cybercriminals are more likely to succeed against smaller targets.  

The financial impact can be devastating.  

Resellers have client trust at stake  

For resellers and service providers, VoIP security isn’t just about protecting your own business. It is about maintaining the trust and confidence of your clients.   

When you recommend VoIP solutions, you’re not just selling technology; you’re staking your reputation on its security. Security breaches can affect client relationships built over years, and it is possible that resellers lose the ability to win new business after security failures.  

Common VoIP Security Threats to Watch For  

Understanding the specific threats targeting VoIP systems and phone calls is your first line of defense. These attacks range from simple eavesdropping to sophisticated financial fraud schemes that can devastate businesses overnight.   

Here’s what’s hunting your phone system right now:  

Eavesdropping and unencrypted traffic  

Your private conversations might not be so private. Unlike traditional phone lines that require someone to physically tap into your building, VoIP calls can be intercepted from anywhere on the internet.   

If your calls aren’t encrypted, every word you speak is traveling in plain text across networks that cybercriminals monitor 24/7.  

SIP attacks and account takeovers  

Session Initiation Protocol (SIP) manages your calls, but it’s also the most targeted entry point for cybercriminals. Once they’re inside your SIP accounts, attackers can take complete control of your phone system.  

Common entry points:  

• Default passwords on devices and accounts  

• Weak authentication protocols  

• Unpatched system vulnerabilities  

RELATED: Learn more about Phishing and Robocalls  

VoIP phishing (vishing)  

Vishing attacks are getting scary good at impersonating trusted organizations. With VoIP’s caller ID spoofing capabilities, attackers can make their calls appear to come from your bank, your IT department, or even your CEO.   

The pressure tactics and apparent legitimacy make these attacks devastatingly effective. How vishing attacks work:  

• Attackers spoof caller ID to impersonate trusted organizations  

• Pressure tactics create urgency (account compromised, immediate action needed)  

• Employees provide credentials or sensitive information  

Toll fraud and unauthorized usage  

Toll fraud represents the most financially devastating VoIP threat. Cybercriminals hijack your system to place thousands of expensive international calls to premium-rate numbers.   

The worst part? You don’t find out until you receive a bill that could shut down your business permanently.  

Denial-of-Service (DoS) on VoIP systems  

DoS attacks don’t steal your data, they steal something even more valuable: your ability to communicate with customers when they need you most.  

They work by overwhelming a VoIP system with a massive volume of fake call setup requests, essentially creating digital traffic jams that consume all available network resources.   

How to Secure VoIP Calls: Best Practices  

The good news is that implementing comprehensive VoIP security doesn’t require a computer science degree or a massive IT budget.   

Follow these cybersecurity battle-tested strategies to protect your communications without breaking the bank or overwhelming your team:  

1. Use End-to-End Encryption (SRTP & TLS)  

2. Set Strong Passwords and Multi-Factor Authentication  

3. Secure Your Network with Firewalls and VLANs  

4. Keep Your PBX and VoIP Software Updated  

5. Monitor Call Logs and Usage Patterns Regularly  

6. Educate Staff and Clients on Social Engineering Risks  

7. Encryption Standards and Transparent Security Practices  

8. Control Over Configuration (BYOD, API Access)  

9. Support for Number Portability and Compliance  

10. No Black Box — Full Visibility Into Your Setup  

Use End-to-End Encryption (SRTP & TLS)  

Call encryption is your nuclear option against eavesdroppers, representing a secret code that only you and your caller understand (except this code is mathematically unbreakable).  

Leading VoIP service providers understand the critical importance of encryption and offer comprehensive call protection through SIP Transport Layer Security (SIP-TLS) and Secure Real-Time Transport Protocol (SRTP) on every call when enabled.   

Want to understand VoIP encryption? Click here and see why encryption protocols can protect your business from eavesdropping attacks.  

This dual-layer protection ensures both your call setup and voice data remain secure throughout the entire conversation. See how to implement it with VoIP.ms:  

Step 1: Enable encryption in your customer portal  

• Go to Customer Portal > Main Menu > Account Settings  

• Navigate to Advanced section and find “Encrypted SIP Traffic”  

• Set to “Yes” and press Apply (applies to all SIP traffic on main account)  

Step 2: Configure your devices for encrypted calls  

• Set transport protocol to TLS in your device settings  

• Activate SRTP as “Mandatory” (prevents unencrypted calls)  

• Use numbered server names (chicago1.voip.ms instead of chicago.voip.ms)  

Step 3: Verify encryption is working  

• Check Portal Home for green padlock icon next to “Registered”  

• Confirm TLS uses port 5061 (not standard 5060)  

• Contact support for manual certificates if needed (expire every 90 days)  

Set strong passwords and multi-factor authentication  

Here’s the uncomfortable truth: most breaches happen because someone used “password123” or left default credentials unchanged. Using strong authentication creates multiple barriers that force attackers to give up and find easier targets.  

Multi-Factor Authentication (MFA) adds a critical second layer of protection beyond passwords. Even if hackers crack or steal your credentials, MFA blocks them from accessing your VoIP system by requiring additional proof of identity.   

Get comprehensive guidance on VoIP security monitoring and incident response to protect your business from authentication attacks.  

Secure your network with firewalls and VLANs  

Network security creates the first barrier between cybercriminals and your VoIP system by implementing packet filtering, intrusion detection, and traffic segmentation at the network perimeter.   

Properly configured firewalls inspect SIP traffic patterns, block malicious IP ranges, and prevent unauthorized access attempts before they reach your PBX or VoIP endpoints.   

See how to setup with VoIP.ms:  

1. Configure essential VoIP ports: SIP (5060-5080 UDP/TCP), SIP-TLS (5061-5081 TCP), RTP (10001-20000 UDP)  

2. Set bidirectional traffic rules for incoming and outgoing connections  

3. Disable SIP ALG and SPI Firewall settings on routers to prevent connection issues  

4. Whitelist authorized VoIP provider IP addresses for secure network access  

Lear more about Firewalls with our Wiki article.   

In addition, virtual networks (VLANs) let you split your physical network into separate logical networks without buying additional hardware. This separation boosts network performance, strengthens security, and improves traffic management.  

Keep your PBX and VoIP software updated  

Outdated software is like leaving your front door unlocked. Every day you delay updates, hackers gain new ways to break into your system. Software updates can close security holes that criminals are actively exploiting right now.  

RELATED: Still on the fence about your PBX phone system? This blog post can help!   

Monitor call logs and usage patterns regularly  

Most businesses discover toll fraud (among other security vulnerabilities) only after receiving devastating bills. Smart monitoring catches attacks in progress, not after the damage is done.   

VoIP.ms Call Detail Records (CDRs) provide comprehensive information about all incoming and outgoing calls on your account, with no limitations on date ranges.   

Access your CDRs through Customer Portal > Finances > Call Detail Records to analyze calling patterns and identify potential security threats.  

Educate staff and clients on social engineering risks  

No amount of technical security can protect against an employee who hands over credentials to a convincing caller. On the other hand, most social engineering attacks fail when people know what to look for.  

What to Look for in a Secure VoIP Provider  

Not all VoIP providers are equal, and yours becomes your security partner, not just your phone service. Choose wisely, and you get protection without complexity.  

Encryption standards and transparent security practices  

Trustworthy telephony providers don’t hide behind technical jargon or treat security as a premium add-on. They make comprehensive encryption standard, not optional, and they’re proud to explain exactly how they protect your business.  

Why does VoIP encryption matter for your business? As personal and confidential data flows through VoIP networks, call encryption becomes essential for maintaining data integrity and preventing unauthorized access.  

Control over configuration (BYOD, API access)  

A secure and scalable BYOD strategy requires managing risks from employee-owned devices accessing corporate VoIP systems. The real security challenge is controlling data access from those devices to your communications infrastructure.  

Modern VoIP providers offer SOAP and REST/JSON Application Programming Interfaces (APIs) that provide essential functions for managing DID numbers, creating sub-accounts, checking balances, and more.  

These APIs allow you to integrate VoIP functionalities directly into your website, intranet, extranet, or customer portal, but they also create new security requirements for BYOD environments.  

BOX: Essential BYOD security controls:  

• VPN implementation to secure data transmission on personal devices  

• Mobile device encryption and authentication for all BYOD endpoints  

• Consistent security policies across hardware phones, software phones, and mobile apps  

• Device management actions to maintain security regardless of device ownership 

RELATED: What is a Bring Your Own Device (BYOD) plan?   

Support for number portability and compliance  

Regulatory compliance isn’t optional, and neither is your ability to leave if service quality drops. The right provider makes compliance automatic and ensures your phone numbers remain yours, no matter what.  

STIR/SHAKEN compliance is mandatory for U.S. phone numbers and helps combat caller ID spoofing and robocalls. As of June 20, 2025, providers with STIR/SHAKEN must obtain their own certificates and implement the protocol directly.   

Stay ahead of STIR/SHAKEN requirements and protect your business from compliance penalties.  

Look for providers with clear policies for number transfers, minimal fees and straightforward porting processes, and comprehensive support throughout the transfer.   

Full visibility into your setup  

Avoid providers who treat their VoIP phone systems like state secrets. You need complete visibility into your communications infrastructure, real-time monitoring capabilities, and the ability to understand exactly how your business phone system is configured and protected.  

Providers should offer real-time CDRs with export capabilities, monitoring dashboards accessible to non-technical staff, and configuration backup and documentation services.   

Advanced Tips for Resellers Securing Multi-Client Environments  

Managing security across multiple client environments seems overwhelming, but the right approach turns complexity into competitive advantage. These strategies help you deliver enterprise-grade security while maintaining healthy profit margins:  

1. Isolate client accounts with multi-tenant setups  

2. Use API controls to automate secure provisioning  

3. Create standard security templates for clients  

Isolate client accounts with Multi-Tenant Setups  

Proper client isolation prevents security incidents from spreading across your customer base while simplifying management and compliance. Implement dedicated sub-accounts for complete client separation, with individual call routing and security policies per client.   

The multi-tenant infrastructure also allows the management of multiple clients under one unified platform while maintaining complete separation between client environments.  

Use API controls to automate secure provisioning  

API automation ensures every client gets identical, comprehensive security settings while reducing your workload and increasing your scalability.  

BOX: Automation benefits:  

• Reduced human error in security configuration  

• Consistent security standards across all clients  

• Scalable service delivery as client base grows 

RELATED: Here’s everything you need to know about REST API  

Create standard security templates for clients  

Custom security configurations for every client is expensive, time-consuming, and error-prone. Smart templates deliver consistent protection while allowing customization where it matters most.  

Final Thoughts: Secure VoIP Is Smart VoIP  

A robust VoIP security helps to build a foundation for reliable, trustworthy business communications that support growth and customer confidence.  

It requires a systematic approach that addresses technical safeguards like encryption and network segmentation, operational procedures such as monitoring and incident response, and human factors through staff training and awareness programs.   

Security isn’t a one-time setup but an ongoing process of layered protections. With the right provider, proper configuration, and ongoing attention to security best practices, any business can achieve robust protection while maintaining the cost benefits and flexibility that make VoIP attractive.  

Learn all about VoIP.ms’ Business and Reseller Solutions, and experience how we protect your communications infrastructure!  

FAQs About Securing VoIP Calls  

Have a question you don’t see answered here? Ask our Sales Team!     

Is VoIP more or less secure than traditional phones?  

VoIP can be more secure than traditional phones when properly configured. Modern VoIP with encryption, authentication, and monitoring provides stronger protection than traditional phones ever could. Features like end-to-end encryption and real-time fraud detection weren’t available with traditional systems.  

What’s the difference between TLS and SRTP?  

TLS and SRTP protect different parts of your calls and work together for complete security:  

• TLS (Transport Layer Security) encrypts call setup: who you’re calling, caller ID, credentials, routing instructions. This prevents call manipulation and credential theft.  

• SRTP (Secure Real-time Transport Protocol) encrypts voice data during conversation. Even if intercepted, attackers can’t understand the conversation without encryption keys.  

H3: Can SMBs afford enterprise-grade VoIP security?  

Yes, SMBs can definitely afford enterprise-grade VoIP security. Many providers, like VoIP.ms, include basic security features in standard plans without additional charges. The combination of provider features and good practices creates enterprise-grade protection at SMB budgets.