A mobile carrier may selectively offload backhaul data traffic between cell sites and the core network to existing alternative relay networks to increase available backhaul bandwidth to meet higher data traffic demands without adding additional network ‘infrastructure. Data traffic may be offloaded from a cellular network to the alternative relay network based on at least one of a bandwidth capacity of the alternative relay network, a bandwidth availability of the alternative relay network, or a data class of the data. The amount of data that is offloaded to the alternative relay network may then be adjusted based on a blocking probability that is calculated for the alternative relay network.