Surprisingly, using VOIP across an SSL-based VPN can actually improve the call quality (as measured by MOS scores). The improvement seems to be due to encapsulating the UDP VOIP packets ( SIP and RTP ) in TCP/IP. NB Datagram-based VPNs, such as IPSec's ESP are still bad.

According to a study by Sirrix VPN has no negative influence on latency, jitter and packet loss; in the case of the g7.11 codec and compressed VPN it is even possible to gain 10% bandwidth compared to non-VPN traffic. Apart from that, different common VPN solutions have big difference on the available throughput, which is due to the rather small packet sizes and greatly increased overhead:

With enabling authentication, encryption, HMAC, anti-replay attack, and initialization vector, and use small RTP size for Codec, the vpn overhead is high:
g723 with 30ms RTP size and using VPN tunneling: approx. 80% overhead;
g729a with 20ms RTP size and using VPN tunneling: approx. 80% overhead;

But when making some adjustments on the encryption/authentication settings and double the RTP size, the overhead can go down to about 20%-30%, which is affordable for most of cases.

In addition, SBO VPN works to lessen the uses of bandwidth consumption for SIP communication directly by bypassing internet firewall. To make a SIP call with Codec G.729 or G. 723, it consumed about 31.5 kbps bandwidth. But, noticeable matter is that the payload size is only 8 kbps. Rest of the bandwidth is consumed by RTP and other headers. SBO VPN system works here to reduce 80% internet consumption by replaceing the RTP and only transmit payload size.

Comparing to SRTP as encryption method for VoIP: approx. 5% additional overhead.

There is an OpenVPN-based service available on the net which resolves the excessive traffic consumption issue. Several voice packets are placed in the buffer before encapsulation. This minimizes VPN impact and traffic usage doesn't grow with VPN service. This can also help to prevent VoIP traffic detection by packet size, since the size of a single packet is comparable with MTU size (usually 1500 or less).

VoIP and VPN Forums:

VoIP Tunneling methods


Commercial services (in alphabetical order)

  • SBO VPN Solution- It is an innovative solution for VoIP service providers. VoIP services have faced many restrictions and hurdles in many countries of the world. Therefore, it was almost impossible to run business in some parts of the worlds. Business providers were suffering from different types of firewalls or internet blockages issues. But, nowadays, things are different. SBO VPN Solution made it possible to run termination business successfully even in highly restricted network where VoIP is prohibited or not allow. SBO has capacity to bypass any sorts of internet firewall. Therefore, this innovative software opened a horizon of opportunities to start new business.
  • HostedVoIPs-Many countries and states have banned VoIP owing to several political, economical and relevant issues. This makes businesses suffer a major set-back in terms of competition and reach. Tunneled mobile dialers which happen to be the hottest anti-block solution allows the user to make calls successfully via VoIP in low bandwidth areas or in geographies where VoIP traffic is banned. Based on VPN Tunneling technology, these solutions delivers outstanding connectivity and clear sound quality even when the bandwidth is very low or is restricted. The VPN tunnel reduces bandwidth consumption by up to 70% (approx) at the originating end, thereby ensuring smooth and quick transfer of data as well as calls alike. The solutions are based on latest VPN servers and are universally compatible with a wide range of internet enabled devices say Android, iPhone & PC.

  • CryptoVoIP Technologies -HI All, We are original developers (not re-sellers) of VoIP Anti Block Solution and VoIP Dialers working in all VoIP Blocked areas. We provide best rates in the market for VoIP Tunnel as well as VoIP Dialers in whole market. We provide complete re branding and customization of our products as per your business needs and requirement. We also sell complete source code if requested. Start your VoIP Business without any dependency and no need to pay monthly rents. Please contact : sales@cryptovoip.in or visit www.cryptovoip.in for pricing and free demo.

  • iVPN.net - iVPN provides both OpenVPN and L2TP/IPSec connections for VOIP customers from multiple offshore locations. They also support multi-hop networking which allows the chaining of two VPN gateways together for enhanced privacy and anonymity.
  • Optima Saver: Bandwidth Optimization Service for VOIP - Run upto 5 times more calls
  • Road Warrior VPN.com - Road Warrior VPN.com is a OpenVPN (SSL) based VPN provider. They support SNOM phone which run OpenVPN directly on the phone. They also provide easy to use desktop clients.
  • SafeVPN.Net provides VoIP-friendly VPN accounts on UK and US destinations with multiple static IPs. Accounts can work on IPIP, UDP and also on TCP mode to forward VoIP traffic. The service is optimized for VoIP traffic forwarding. Reduces traffic consumption on VoIP Can run on DD-WRT/OpenWRT router firmware.

  • SuperVPN.Net Super VPN offer paid and free PPTP and Open VPN sevices which provide you anonymous web surfing without provider logs for personal and business use.Also they offer VoIP VPN perfect to unblock Skype or any other VoIP software.
  • VPN4SIP.COM - VPN4SIP.COM is a low cost WIFI router based VPN service that UNBLOCKS residential Ethernet VOIP adapters to make SIP or Skype Calls freely in Dubai/UAE, Oman, Qatar and Yemen.
  • Soundwin Soundwin integrate VPN service into its own VOIP products N200 to provide more flexibile communication via VOIP. VPN feature also available on SR series ATA.
  • VPN4VOIP.COM - VPN for VOIP is a low cost SSL based VPN service specially designed for VOIP traffic applications with best service quality in the market. It helps to bypass ISP blocking on VOIP calls utilizing the VPN tunneling technology and assigns mapped static public IP (5 IP with /28 VLAN) to VOIP gateways for wholesale traffic origination and termination applications. The service is QoS controlled, secure, flexible and reliable. User will get guaranteed ping performance and dedicated bandwidth. It is claimed to be working 100% with any ISP - Only one open UDP port is needed to get the solution works. You can use their free deployed client software under Windows XP/2003 with two Ethernet cards which changes the PC into a soft VPN router. Client side can use any dynamic or private IP connections to use the service, free evaluation is available.

  • http://www.vpn3000.com VPN service, this vpn service will let you have privacy for you VOIP calls, and in case of VOIP being blocked, it will let you use VOIP, it is based on SSL, works on Windows, Linux, and Macs. To use it for VOIP if you run asterisk, you can have the asterisk server itself run the openvpn client, in case of an ATA you have to make sure that the ATA traffic goes over the VPN, the ATA could be connected to an Asterisk server running the VPN, or to a Windows or Linux server running the VPN and routing the trafic, the VPN can also be used with some routers that run Linux like Openwrt, or dd-wrt, in the case of a soft phone, you run the vpn on the computer that the soft phone is connected to, the VPN can also be used on some Linux phones, for example Openmoko running debian, or Nokia N810, and N900.

See also

Created by: admin, Last modification: Sun 10 of Jul, 2016 (07:43 UTC) by reve_systems
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