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.
Also
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. 85%
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.
Now we have reached to an optimum configuration that
works for VOIP termination with minimum overhead and
maximum voice quality.
For checking all compatibilities between our VPN
solution and your ISP , we provide you a 12 hours
trial VPN client to see all possible issues and
conflicts. Then you can pay for real client(s) and do
your business.
Our VPN service includes 24/7
technical support via online chat, ticketing and
e-mail. You can check our VPN service rates here and
make a payment there via various payment methods.
