hosted PBX/VOIP thru VPN?

Tim Sanderson tims at
Wed Nov 12 03:24:21 UTC 2008

Yes, dissuade him. If anything a VPN will add latency unless possibly gear is replaced to provide the VPN that is significantly greater than current. But... if a provider en-route decided to "slow down" competing voice traffic, the VPN would hide it from the filters which might make it seem like voice traffic was speeding up. Of course that is a major "if".

Shouldn't take much to lab it, and show the customer the difference in quality, if any. Regardless, if the customer insists, it's billable so why not you than someone else. Just make sure said customer knows that you are not recommending the solution and why. If you implement the VPN and voice quality does not improve, you are covered.

Tim Sanderson, network administrator
tims at

-----Original Message-----
From: Lorell Hathcock [mailto:lorell at]
Sent: Tuesday, November 11, 2008 9:17 PM, if any
To: nanog at
Subject: hosted PBX/VOIP thru VPN?


My customer wants to try to improve performance to his ATAs by creating a VPN from his network to the VOIP provider's network through the internet.

I have to admit, the idea caught me flat footed.  At the outset, it seems like we would want to do it just to improve security for end users. However, my customer wants it because he thinks it will improve performance (i.e.
voice quality).  We are suffering from poor VOIP quality due to the Sprint / Cogent depeering and subsequent squirming by our vendors.

The only reason I can think that VOIP thru a VPN would help is that
*perhaps* routers in the middle on ASNs I have no control over *may* prioritize VPN traffic higher than regular traffic.  They opposite could also be true.

Specifically the ASNs in the middle are Level 3, Sprint and Time Warner.

Thoughts?  Should I try to dissuade him from this if performance is his main motivator?



Lorell Hathcock | 832-665-3400 (o) | 713-992-2343 (f) | lorell at


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