What Is a VoIP VPN? Everything You Need To Know

A virtual private network (VPN) is a tool you can use to encrypt your internet connection, making all of your online activities safer and more private. VPNs can be used for everything from browsing the web to making VoIP phone calls.

You can use a VoIP VPN whether you’re setting up a VoIP phone system for the first time or want to make your existing phone system more secure. In this guide, we’ll explain everything you need to know about VoIP VPNs, from when to use one to how to choose the best one for your phone system.

What Is a VoIP VPN?

A VoIP VPN is any VPN that you use in combination with a VoIP phone system, which makes phone calls over the internet. A VoIP VPN encrypts your communication so that no one can listen in on your calls or even know that you’re making a call in the first place.

VoIP VPNs usually aren’t VoIP-specific. Instead, they are general-use VPNs that are also active when you place a VoIP phone call.

How Does a VoIP VPN Work?

A VPN works by establishing an encrypted internet connection between your device and a server. For VoIP calls, your device is typically your phone, smartphone, or computer, and the server you connect to is typically your VoIP provider’s server.

You can think of a VPN-encrypted connection as a tunnel. Data passes from your device to your VoIP server and back, but no one can penetrate the VPN tunnel to access your data. This means no one can listen in on your calls.

One thing to note is that most top VoIP phone providers offer connections that are already end-to-end encrypted. This means that you don’t necessarily need a VPN to prevent bad actors from listening in on your calls. However, combining your VoIP phone system’s built-in encryption with a VPN can make your communications even more secure.

Types of VPN for VoIP: site-to-site, remote-access, ZTNA and SD-WAN

There are, broadly speaking, four types of VPN setup you can opt for.

Site-to-site VPN (office ↔ office/datacenter)

What it is: A VPN that permanently links two whole networks, for example, your branch office and your HQ/datacenter, so they behave as if they’re on the same private LAN. It’s usually built with IPsec (Internet Protocol Security) on your firewalls/routers, so no user app is needed.

When it helps VoIP: Ideal if you host voice gear centrally (an on-prem PBX, Private Branch Exchange, or an SBC, Session Border Controller) and want branches to reach it securely. Voice media travels directly between sites without going over a user’s personal VPN.

Quality tip: Keep real-time audio on UDP (User Datagram Protocol) and prioritise it using QoS (Quality of Service)/ DSCP (Differentiated Services Code Point) so voice packets don’t get stuck behind bulk traffic.

Remote-access VPN (individual users ↔ company network)

What it is: A user-to-network tunnel made by a VPN client app on a laptop or phone. It’s great for reaching internal apps when you’re at home or travelling.

When it helps VoIP: Useful if remote staff need intranet tools and to place calls. However, routing live voice/video through a full VPN can add delay or block the preferred UDP path.

What to do: Use split tunnelling (only sensitive apps go through the VPN; VoIP media flows directly to the provider). Avoid “full-tunnel” or “hairpin” setups that send every packet (including calls) through a distant VPN gateway.

ZTNA (Zero Trust Network Access)

What it is: Instead of putting a device on your network via VPN, ZTNA checks who the user is (identity), what device they’re on (health/posture), and then opens access only to specific apps, rather than the full network. Think of it as “app-by-app doors,” often delivered from the cloud.

When it helps VoIP: Perfect for protecting the apps around your phone system (admin portals, analytics, call recordings, CRM) while letting real-time voice/video take the shortest, most reliable internet path to your VoIP/UCaaS provider.

SD-WAN (Software-Defined Wide Area Network)

What it is: A smart WAN layer that steers traffic over multiple links (fibre, broadband, 5G) based on live performance and policy. Many platforms add voice-friendly features like packet duplication or FEC (Forward Error Correction) to smooth out loss.

When it helps VoIP: Multi-site organisations, or any location with variable circuits. SD-WAN can prefer the cleanest path for RTP (Real-time Transport Protocol, the audio stream), fail over mid-call, and enforce QoS/DSCP consistently across sites.

When Should You Use a VoIP VPN?

Using a VPN for your VoIP phone system can be helpful in several instances.

Sensitive Communications

Using a VoIP VPN can make your company’s most sensitive communications more secure by adding another layer of encryption to your calls.

This is important because VoIP phones have been hacked in the past despite having their own encryption systems. With a VPN, you can feel confident that your phone calls are secure since it’s virtually impossible to break through two layers of encryption at the same time.

Public WiFi Networks

If you’re making VoIP phones on the go—for example, at the airport on the way to a business meeting—your calls could be vulnerable to malicious actors even if they’re encrypted. That’s because public WiFi routers can be hacked and used to intercept your communication data.

Using a VPN addresses this problem by encrypting communication data before it ever leaves your device. The VPN tunnel then protects that data from being stolen even if it passes through a compromised router.

Avoiding VoIP Firewalls

Some countries, including China, Mexico, and Saudi Arabia, have blocked most VoIP communications to enable more surveillance of communications or protect incumbent telecom providers. If you’re in one of these countries or need to call one of these countries, your VoIP phone might not work.

A VPN solves this problem by masking the IP address of your device, making it harder for firewalls to recognize that incoming data originated from a VoIP phone.

Preventing Bandwidth Throttling

Some internet service providers (ISPs) may throttle your internet bandwidth if they see that you’re using your connection to make VoIP calls. This is designed to encourage you to upgrade your internet plan, even if an upgrade isn’t necessary.

Using a VoIP VPN makes it impossible for your ISP to determine whether you’re making VoIP calls, so they’re less likely to throttle your connection.

When not to use a VPN for VoIP (and what to do instead)

There are occasions where it may be beneficial not to use a VPN, if at all possible.

Skip full-tunnel VPNs for real-time voice and video

Full-tunnelling your VoIP or Unified Communications (UC) software traffic through a VPN adds latency and hairpins traffic through congested gateways, degrading call quality. Microsoft, Zoom and Cisco advise split tunnelling so media flows directly to their clouds, while non-real-time apps still use the VPN.

Don’t hairpin traffic through distant or overloaded gateways

Routing calls via a far-away or busy VPN concentrator increases round-trip time and jitter. Let clients reach the provider’s nearest edge directly and keep the VPN for apps that truly need it.

Choosing a VoIP VPN: Features To Look For

Now that you know why to use a VoIP VPN, how do you choose the right one? Here are some of the key features to consider when comparing VPN providers.

Connection Speed

All VPNs will slow down your connection speed slightly, and that’s okay. But if your VPN slows down your connection too much, it can lead to VoIP latency or other issues.

Look for VPN providers that offer modern, high-speed VPN protocols such as WireGuard or OpenVPN.

Wide Range of Servers

Long distances between your device and your VPN server can also contribute to slow connection speeds. It’s important to choose a VPN provider that has a wide range of servers around the world so that there’s always one nearby. Top VPN providers typically have thousands of servers spread across dozens of countries.

No-log Policy

Many VPN providers have what’s known as a no-log policy, meaning they never keep logs of your internet activity. This means that your VPN provider can’t be compelled to turn over information about your call history—they simply don’t have that information.

Mobile Apps

If you plan to make VoIP calls from your smartphone, ensure your VPN provider offers user-friendly mobile apps. You can activate your VPN on your phone before making a call and it will encrypt your connection regardless of whether your call is placed over WiFi or cellular data networks.

Split Tunnelling

Split tunnelling is a feature that allows you to activate your VPN for some apps on your device, but not others. For example, you can activate your VPN for VoIP calls, but not for browsing.

This is useful if you want to make encrypted phone calls with a VPN but still need to access your company’s internal network or geographically restricted websites with your browser.