A system and method are provided for securely establishing Layer-3 SVCs or SPVCs across an ATM network. An originating multiservice switch that generates the connection setup message for the Layer-3 connection includes security information within the setup message, such as a Closed User Group Interlock Code. When the destination multiservice switch receives the setup message, it extracts the embedded security information and compares it with stored security information corresponding to the connection. The correspondence may be determined from the destination user. If the embedded security information matches the stored security information, the destination multiservice switch allows the connection to be established.