Important Details of Virtual Private Network and its Relation to VoIP

Virtual Private Network is a connection method which adds security and privacy to private and public networks. In short, it provides a safer Internet experience to the user.

Virtual Private Network


Virtual Private Network or VPN is the technology that creates a safe and encrypted connection over a less secure network, for instance, the internet. In other words, VPN is a private network that uses a public network like the internet to connect to remote sites or users together. But this is not the first technology to make such connections. Previously, leashed lines were there to connect computers between multiple offices. These are private network connections that a telecommunication company offered to their customers. But the leased lines through reliable and secure were expensive. And with time when a company expanded, the cost for this increased as well. VPN solves this problem. It uses the virtual connections routed through the internet from the business’s private network to a remote site or employee. Applications running across VPN, therefore, benefit from the functionality, security and management of the private network.




Types of VPN

Establishing a virtual point-to-point connection through the use of dedicated connections, virtual tunnelling protocols or traffic encryption leads to the creation of VPN.


There are 2 basic types of Virtual Private Network:

Remote Access VPN

Remote Access VPN allows users to connect to a private network and access its service and resources remotely. The user and the private network connection through the internet. This connection is secure and private. This type of Virtual Private Network is useful for both business users as well as home users. While on the go, this enables corporate workers to connect to the company’s private network and remotely access files and resources on the private network. For individual users, VPN service helps to bypass regional instructions on the internet and access blocked websites.


Site-to-Site VPN

Site-to-site VPN or Router-to-Router VPN is mostly useful for corporates. Companies with multiple office branches in different locations use this VPN to connect the network of one office location to the other. Intranet-based VPN is where multiple branch offices of the same company connect using site-to-site VPN. Extranet-based VPN connects to the office of another company. In this type of VPN one router acts as a VPN client while the other as a VPN server. The communication starts after validation and authentication between them.



Types of VPN Protocol

Virtual Private Network Protocols are the combination of encryption standards and transmission protocols which determine data routing and its management. Each protocol offers different benefit from the other. The VoIP Gateway router first converts the analogue 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 analogue signal for delivery to the phone. To know more about tunnelling protocol in VoIP check here: Importance of Tunnelling Protocol in Mobile Dialer


Internet Protocol Security (IPSec)

Internet Protocol Security enables secure Internet communication across an IP network. It secures Internet Protocol communication. It authenticates the session and encrypts each data packet during the connection. There are 2 modes of operation for IPSec to protect data transfer between two different networks. Firstly, the transport mode. Secondly, tunnelling mode. The transport mode encrypts the message in the data packet. While the tunnelling mode encrypts the entire data packet. Usage of IPSec with other security protocols helps to enhance the security system.


Point-to-Point Tunnelling Protocol (PPTP)

PPTP or Point-to-Point Tunnelling Protocol creates a tunnel and encapsulates the data packet. It uses a Point-to-Point Protocol (PPP) to encrypt the data between the connections. This is one of the most widely used VPN protocol. Furthermore, this protocol dates back to the time of Windows 95. Apart from Windows, PPTP is also supported on Mac and Linux.


Layer 2 Tunnelling Protocol (L2TP)

Layer 2 Tunnelling Protocol is a tunnelling protocol that is usually combined with another VPN security protocol like IPSec to create a highly secure VPN connection. L2TP creates a tunnel between two L2TP connection points and IPSec protocol encrypts the data and handles secure communication between the tunnels.


Secure Sockets Layer (SSL) & Transport Layer Security (TLS)

SSL (Secure Sockets Layer) and TLS (Transport Layer Security) create a VPN connection where the web browser acts as the client and user access is restricted to specific applications instead of the entire network. SSL and TLS protocol are most commonly used by online shopping websites and service providers. Web browsers(integrated with SSL and TLS) switch to SSL with ease and with almost no action required from the user. SSL connections have https at the beginning of the URL instead of HTTP.


Secure Shell (SSH)

Secure Shell or SSH creates the VPN tunnel through which the data transfer happens and also ensures that the tunnel is encrypted. An SSH client creates the SSH connections. In this, the data transfer takes from a local port on to the remote server through the encrypted tunnel



OpenVPN is an open source VPN that is useful for creating Point-to-Point and Site-to-Site connections. It uses a custom security protocol based on SSL and TLS protocol.




VoIP and VPN

VoIP VPN combines Voice over IP and Virtual Private Network technologies to offer a method for delivering secure voice. In other words, VoIP VPN creates a secure, encrypted tunnel over the Internet through which all the VoIP Traffic passes through. This results in bypassing firewall restrictions and make calls secure. VoIP VPN further hides the real IP address. It assigns a new address based on the selected VPN server. This makes the person anonymous online. It, therefore, allows one to access VoIP Service even through VoIP blockage.

Using VoIP across an SSL based VPN improves the call quality. Apart from bypassing VoIP blockages, VoIP VPN also provides strong security due to its encryption. The encryptions ensure that all VoIP conversations are protected from data retention along with preventing any attempt of throttling bandwidth. Also in addition to this, VPN has no negative influence on latency, jitter and packet loss.



Advantages of VoIP via VPN

  • Cost Reduction: Although VoIP reduces call cost as compared to the PSTN services by a significant amount, the use of VPN can bring it down further. Connecting to the VPN server of specific or concerned countries will result in a cheaper call. Simply put, VoIP via VPN compares the prices of a VoIP Provider through different countries and choose accordingly.
  • Prevent Throttling: When data is used continuously then there are chances that the Internet Service Provider (ISP) throttle the bandwidth. If that happens then it results in degradation of call quality. Here VPN prevents the ISP from seeing the traffic and thus avoid the throttling.
  • Security: Using VPN for VoIP secures the entire internet connection with strong encryption. This prevents anyone from prying into or intercepting any data.
  • Bypassing blockages: There are many regions around the world with VoIP blockages. VPN helps to bypass these blockages and use VoIP Service freely.




Virtual Private Network undoubtedly is one of the useful technologies in the present day. It makes online activity safe and secure. The new VoIP encryption standards built into the protocol, such as ZRTP and SRTP, allow the VoIP client to run without the VPN overhead. They integrate the VPN with standard features of VoIP PBX without having to manage both the VPN gateway and the PBX.


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