If you check the Count non-ACD calls in utilization capacity check box, Genesys Cloud factors in the internal calls between agents for calculation of agent capacity. Therefore, if the voice capacity is set to one call, and an agent is on a non-ACD call, Genesys Cloud does not route the incoming ACD call to the agent as the capacity has been reached. However, if the voice capacity is set to two, the ACD call can still interrupt the non-ACD call. For more information, see Block calls when on a non-ACD call (excludes transfers).