In this paper, we provide a new availability analysis of backhaul wireless communication networks which are supported by microwave links which evolved out of sharing between two different mobile network operators (MNOs) based on the Multi-State System (MSS) approach using Discrete-state Continuous-time Markov chain model. Our results show that such a jointly- constructed network was available to meet the required demand of the total system more than 99.8 % of the time.