Opensips as Load Balancer
traffic routing based on load and avaiable slot of destinations Opensips is aware of the capacity of each destination as it is preconfigured with the maximum load accepted by the destinations aware of the load status (as number of ongoing calls) of each destination will share traffic accordingly with less loaded destinations feedback from gdestination to update routing rules
Ref : https://www.opensips.org/Documentation/Tutorials-LoadBalancing