AT&T Corp has begun roll-out of its WorldNet virtual private network service (VPNS) based on its IP backbone. It offers dial- up access from more than 300 points of presence (PoPs) – with 375 on line by the year end – dedicated frame relay service linking corporate LANs to the backbone, with private line links coming next March and international access planned from 35 countries via ISDN and dial-in, with more to come.