1. A method, comprising: at a conferencing system constructed to operate scalable conferencing services, the conferencing system including a conference orchestration service, a conference state manager, a mixer state manager, and a set of distributed mixers: receiving a request for a new conference via at least one of application layer interface of the conferencing system and a signaling protocol communication interface of the conference orchestration service; allocating mixers of the conference, the mixers being mixers of the set of distributed mixers; and negotiating media across the allocated mixers, wherein receiving a request for a new conference comprises determining participants of the conference, wherein allocating mixers of the conference comprises: generating a mixer topology that specifies an assignment of each determined participant to at least one input channel of at least one mixer of the set of distributed mixers, wherein negotiating media across the allocated mixers comprises routing media of each determined participant to the assigned at least one input channel, and starting the conference, wherein the media is routed according to the generated mixer topology, and wherein the mixer state manager generates the topology responsive to an application layer request provided by the conference state manager, the conference state manager provides the application layer request responsive to an application layer request provided by the conference orchestration service, the routing is performed by the conference orchestration service in accordance with a signaling protocol, and the conference orchestration service receives the generated mixer topology from the mixer state manager via the conference state manager.