In this paper we analyze the performance of a downlink single user multi-cellular multiple inputs single output (MISO) system using the Alamouti code. We derive, for the first time, an analytical expression of the cumulative distribution function of the output signal to interference plus noise ratio (SINR) or equivalently the outage probability in flat Rayleigh fading. The system is considered interference limited. Two assumptions are considered: equal received power and unequal received power from the interfering base stations. In the first case, a closed-form expression for the outage probability is derived. In the second case, from an approximation of the interference power distribution the outage probability expression is obtained.