VOIP / VPN -- call quality ?

Do you know if anyone else has done VOIP via VPN successfully since our main concern is call quality ?

We are thinking about doing the below VOIP via VPN.

1.      Purchase VOIP PBX for each of our four locations

2.      Have user in one location (10mb/sec fiber connection) call user in another location (10mb/sec fiber connection) non-MPLS network

Below are some articles I read:

http://itknowledgeexchange.techtarget.com/channel-marker/how-to-run-voip-across-vpn-with-some-qos-assurance/

http://forums.untangle.com/openvpn/18212-voip-through-vpn-qos-issues.html

http://www.cisco.com/en/US/products/ps6120/products_configuration_example09186a008080dfa7.shtml
finance_teacherAsked:
Who is Participating?

[Product update] Infrastructure Analysis Tool is now available with Business Accounts.Learn More

x
I wear a lot of hats...

"The solutions and answers provided on Experts Exchange have been extremely helpful to me over the last few years. I wear a lot of hats - Developer, Database Administrator, Help Desk, etc., so I know a lot of things but not a lot about one thing. Experts Exchange gives me answers from people who do know a lot about one thing, in a easy to use platform." -Todd S.

Qlemo"Batchelor", Developer and EE Topic AdvisorCommented:
There are a lot of issues with VoIP over VPN (or any other tunnel technique). Some of them are:
QoS/DSCP flags are not honoured at all with the VPN packets, because ISPs are interested in managing that themselves for different services
The VPN gateway device is not able to move or apply the QoS setting of VoIP traffic to the encapsulating VPN packets
Depending on the power of the VPN device, and the used encryption and hashing algorithms, the device introduces significant lag and overhead to the VoIP packets
Only with carefully chosen devices, and ensuring to have a priorised VPN route between locations, you will have good results. It is much to prefer to have a direct VoIP connection, without applying NAT and IPSec (or SSL) encryption.
José MéndezCommented:
Let me share my little experience with this topic:

I was able to connect a very good quality voip call from my girlfriend's house to mine with the following components:

- Asterisk 1.8
- OpenVPN 2.2.2
- Granstream GVX3140
- 512kbps connection on phone's location
- 4Mbps connection on Asterisk's side
- Regular domestic modem/routers at each side

The call used G.711 and it was crystal clear as not even myself would believe it. Now, as Qlemo stated, it can get dirty when there are no QOS settings in place. Just image one of the locations streaming Youtube videos.... your voice clarity is most likely gone... But it is possible however, that's what I wanted to share.

HTH
Frank MayerTechnical Voip SupportCommented:
Well,
your internet access looks good. Why not first checking wether there are VoIP Providers which provide security and a virtual PBX to configure via Web eg. ? What is your interest in setting up all yourself (besides learning alot :)) ?

Experts Exchange Solution brought to you by

Your issues matter to us.

Facing a tech roadblock? Get the help and guidance you need from experienced professionals who care. Ask your question anytime, anywhere, with no hassle.

Start your 7-day free trial
It's more than this solution.Get answers and train to solve all your tech problems - anytime, anywhere.Try it for free Edge Out The Competitionfor your dream job with proven skills and certifications.Get started today Stand Outas the employee with proven skills.Start learning today for free Move Your Career Forwardwith certification training in the latest technologies.Start your trial today
Voice Over IP

From novice to tech pro — start learning today.