Conferencing represents an important category of applications, which includes videoconferences and distance learning. To our knowledge, there is no signaling architecture for conferencing in integrated 3G/mobile ad hoc networks. However, there are architectures for conferencing in stand alone 3G and in stand alone mobile ad hoc networks. Unfortunately, none are suitable when the two networks are integrated. This paper proposes a novel signaling architecture for conferencing in integrated 3G/mobile ad hoc networks. This architecture is based on application-level clusters and conference gateways. The gateways mediate between the 3G and the mobile ad hoc networks. We have implemented a prototype using the Session Initiation Protocol as our technology.