You can run VOIP across the internet with vpn tunnels. The only problem exists is that there is no honoring of prioritization. Especially considering that your tunnel is encrypted. Service providers wont be able to read those precedence bits or any dscp values that are represented in the vpn tunnel. You can use the QOS pre-classify option that will try and push all of the "ef"
(voice) traffic into the tunnel first and give it priority thru the tunnel. That's about all you can do. At least that I know of. search QOS and VPN tunnels and you should find more information about it.
Table of ContentsIntroductionVersion HistoryPossible Future
UpdatesDocuments PurposeNAT Operation in ASA 8.3+ SectionsRule Types
Network Object NATTwice NAT / Manual NATRule Types used per SectionNAT
Types used with Twice NAT / Manual NAT and Network Obje...
[toc:faq]Introduction:This document describes details on how NAT-T
works.Background:ESP encrypts all critical information, encapsulating
the entire inner TCP/UDP datagram within an ESP header. ESP is an IP
protocol in the same sense that TCP and UDP are I...