On Monday, I posted an article regarding an upcoming SIP Trunking webcast. In that article, I suggested that you can implement a Sip Trunk without a PSTN gateway. For the most part this is the case, but as one reader, Andy McAllister, pointed out, you probably are going to want a Session Boarder Controller to terminate the VPN between you and the SIP Provider. So the rosy picture painted in the earlier article is not altogether correct. Having said that, SIP Trunks typically offer lower cost telephony as well as increased flexibility in provisioning and de-provisioning.