There is no QOS over the public internet..vpn or not. It has to be a mangaged service such as a t-1, t-3 pri or metro e. And with managed services you still need a miminum bandwith (typically 256 base and 112 kb per voip call) for H.323 up and down to not have jitter or latency.

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"Old phone guys never die, they just get locked in some closet with an old phone system and forgotten about"

Retired, taking photographs and hoping to fly one of my many kites.