One of the snags in VoIP installations is how to extend them to small branch offices or home offices (which are getting more common in all industries that rely on knowledge workers). According to IDC, VoIP is growing faster in home offices than in corporate offices.
Connecting a corporate VoIP network across the Internet, to a home office or a hotel (once it’s outside the firewall, does it really matter from where a remote worker is connecting?) so telecommuters and travelling employees can connect with it is daunting. It’s hard enough (and expensive enough) to get acceptable VoIP performance in a corporate setting.
Cisco is offering some corporate/home VoIP configuration guidance, in a document, in a paper that — judging by the rule that the usefulness of any technical document rises in direct proportion to the awkwardness with which it’s written — is very useful indeed: PIX/ASA 7.x: QoS for VoIP Traffic on VPN Tunnels Configuration Example
(Here’s some advice on how to set up a comfortable and productive home office, btw.)