Note: When the Gateway uses H.323 Fast Start, the OpenLogicalChannel message timer expires before Cisco CallManager can respond with the acknowledgement (ACK) and the IP address of the remote phone. Therefore, the Gateway sends the disconnect before Cisco CallManager can route the call. If incoming calls from FXO are disconnected, you should use Slow Start (which is the default unless you check the Enable Inbound FastStart on the Gateway Configuration page). This will give enough time for the OpenLogicalChannelAck to arrive before the Gateway sends the disconnect.