A VoIP VPN combines

voice over IP Voice over Internet Protocol (VoIP), also known as IP telephony, is a set of technologies used primarily for voice communication sessions over Internet Protocol (IP) networks, such as the Internet. VoIP enables voice calls to be transmitted as ...

and

virtual private network Virtual private network (VPN) is a network architecture for virtually extending a private network (i.e. any computer network which is not the public Internet) across one or multiple other networks which are either untrusted (as they are not con ...

technologies to offer a method for delivering

secure voice Secure voice (alternatively secure speech or ciphony) is a term in cryptography for the encryption of voice communication over a range of communication types such as radio, telephone or Voice over IP, IP. History The implementation of voice en ...

. Because VoIP transmits digitized voice as a stream of data, the VoIP VPN solution accomplishes voice

encryption In Cryptography law, cryptography, encryption (more specifically, Code, encoding) is the process of transforming information in a way that, ideally, only authorized parties can decode. This process converts the original representation of the inf ...

quite simply, applying standard data-encryption mechanisms inherently available in the collection of protocols used to implement a VPN. The VoIP gateway-router first converts the analog voice signal to digital form, encapsulates the digitized voice within IP packets, then encrypts the digitized voice using IPsec, and finally routes the encrypted voice packets securely through a VPN tunnel. At the remote site, another VoIP router decodes the voice and converts the digital voice to an analog signal for delivery to the phone. A VoIP VPN can also run within an

IP in IP IP most often refers to: * Intellectual property, creations of the mind for which exclusive legal rights are recognized * Internet Protocol, a set of rules for sending data across a network IP or Ip or ip may also refer to: Businesses and organi ...

tunnel or using SSL-based

OpenVPN OpenVPN is a virtual private network (VPN) system that implements techniques to create secure point-to-point or site-to-site connections in routed or bridged configurations and remote access facilities. It implements both client and server appl ...

. There is no encryption in former case, but traffic overhead is significantly lower in comparison with IPsec tunnel. The advantage of OpenVPN tunneling is that it can run on a dynamic IP and may provide up to 512 bits SSL encryption.

Advantages

Security Security is protection from, or resilience against, potential harm (or other unwanted coercion). Beneficiaries (technically referents) of security may be persons and social groups, objects and institutions, ecosystems, or any other entity or ...

is not the only reason to pass

Voice over IP Voice over Internet Protocol (VoIP), also known as IP telephony, is a set of technologies used primarily for voice communication sessions over Internet Protocol (IP) networks, such as the Internet. VoIP enables voice calls to be transmitted as ...

through a

, however.

Session Initiation Protocol The Session Initiation Protocol (SIP) is a signaling protocol used for initiating, maintaining, and terminating communication sessions that include voice, video and messaging applications. SIP is used in Internet telephony, in private IP telepho ...

, a commonly used VoIP protocol is notoriously difficult to pass through a

firewall Firewall may refer to: * Firewall (computing), a technological barrier designed to prevent unauthorized or unwanted communications between computer networks or hosts * Firewall (construction), a barrier inside a building, designed to limit the spre ...

because it uses random port numbers to establish connections. A VPN is also a workaround to avoid a

issue when configuring remote VoIP clients. However, latest VoIP standard STUN,

ICE Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

and TURN eliminate natively some NAT problems of VoIP. Installing an extension on a VPN is a simple means to obtain an off-premises extension (OPX), a function which in conventional landline telephony required a

leased line A leased line is a private telecommunications circuit between two or more locations provided according to a commercial contract. It is sometimes also known as a private circuit, and as a data line in the UK. Typically, leased lines are used by ...

from the

private branch exchange A business telephone system is a telephone system typically used in business environments, encompassing the range of technology from the key telephone system (KTS) to the private branch exchange (PBX). A business telephone system differs from ...

to the remote site. A worker at a remote location could therefore appear virtually to be at the company's main office, with full internal access to telephone and network.

Disadvantages

The protocol overhead caused by the encapsulation of VoIP protocol within IPSec dramatically increases the bandwidth requirements for VoIP calls, thus making the VoIP over VPN protocols too "fat" to be used over a mobile data connections like

GPRS General Packet Radio Service (GPRS), also called 2.5G, is a mobile data standard on the 2G cellular communication network's Global System for Mobile Communications, global system for mobile communications (GSM). Networks and mobile devices wit ...

EDGE Edge or EDGE may refer to: Technology Computing * Edge computing, a network load-balancing system * Edge device, an entry point to a computer network * Adobe Edge, a graphical development application * Microsoft Edge, a web browser developed by ...

UMTS The Universal Mobile Telecommunications System (UMTS) is a 3G mobile cellular system for networks based on the GSM standard. UMTS uses Wideband Code Division Multiple Access, wideband code-division multiple access (W-CDMA) radio access technolog ...

. Although VoIP over VPN is not as usable in mobile environments, it is sometimes used to create "encrypted VoIP trunk" between different sites of a corporations, running VoIP PBX interconnections over a VPN connection.

New solutions

The recent publication of new VoIP encryption standards built into the protocol, such as

ZRTP ZRTP (composed of Z and Real-time Transport Protocol) is a cryptographic key-agreement protocol to negotiate the keys for encryption between two end points in a Voice over IP (VoIP) phone telephony call based on the Real-time Transport Protocol ...

and SRTP, allow the VoIP client to run without the VPN overhead, integrating with standard features of VoIP PBX without having to manage both the VPN gateway and the PBX.

Free implementation

VoIP VPN solution may be accomplished with free

open source Open source is source code that is made freely available for possible modification and redistribution. Products include permission to use and view the source code, design documents, or content of the product. The open source model is a decentrali ...

software by using a

Linux distribution A Linux distribution, often abbreviated as distro, is an operating system that includes the Linux kernel for its kernel functionality. Although the name does not imply product distribution per se, a distro—if distributed on its own—is oft ...

BSD The Berkeley Software Distribution (BSD), also known as Berkeley Unix or BSD Unix, is a discontinued Unix operating system developed and distributed by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, beginni ...

as an

operating system An operating system (OS) is system software that manages computer hardware and software resources, and provides common daemon (computing), services for computer programs. Time-sharing operating systems scheduler (computing), schedule tasks for ...

, a VoIP server, and an IPsec server.

References

https://www.pcmag.com/article/365673/when-to-use-a-vpn-to-carry-voip-traffic

Sources

{{Reflist Voice over IP Virtual private networks