A computer implemented method of managing calls using a call manager server for controlling a private network (66A-2) of telephony devices (54A-1, 54A-2, 54A-3) and for providing a connection gateway to a public network (66A-1), comprising: receiving, at said call manager server an incoming call request, initiated by a first telephony device (54A-1), to connect said first telephony device (54A-1) to a second telephony device (54A-3); said first telephony device (54A-1) and said second telephony device (54A-3) each associated with said private network (66A-2); at least one of said first telephony device (54A-1) and said second telephony device (54A-3) being connected to said public network (66A-1); said first telephony device (54A-1) configured to initiate said call request through said call manager server; if said second telephony device (54A-3) is otherwise engaged in another call with a third telephony device (54A-2), determining at said call manager if a preemption request exists to interrupt said another call; if said preemption request exists, determining at said call manager if a preemption policy permits said preemption request; if said preemption policy permits said preemption request, terminating said another call and completing said call request by connecting said first telephony device (54A-1) to said second telephony device (54A-3) using said call manager server; and, if said preemption policy does not permit said preemption request, invoking at said call manager server, a process for managing incoming call requests when said second telephony device (54A-3) is unavailable; if said second telephony device (54A-3) is not otherwise engaged in another call with a third telephony device (54A-2), completing said call request by connecting said first telephony device (54A-1) to said second telephony device (54A-3) using said call manager server. receiving, at said call manager server an incoming call request, initiated by a first telephony device (54A-1), to connect said first telephony device (54A-1) to a second telephony device (54A-3); said first telephony device (54A-1) and said second telephony device (54A-3) each associated with said private network (66A-2); at least one of said first telephony device (54A-1) and said second telephony device (54A-3) being connected to said public network (66A-1); said first telephony device (54A-1) configured to initiate said call request through said call manager server; if said second telephony device (54A-3) is otherwise engaged in another call with a third telephony device (54A-2), determining at said call manager if a preemption request exists to interrupt said another call; if said preemption request exists, determining at said call manager if a preemption policy permits said preemption request; if said preemption policy permits said preemption request, terminating said another call and completing said call request by connecting said first telephony device (54A-1) to said second telephony device (54A-3) using said call manager server; and, if said preemption policy does not permit said preemption request, invoking at said call manager server, a process for managing incoming call requests when said second telephony device (54A-3) is unavailable; if said second telephony device (54A-3) is not otherwise engaged in another call with a third telephony device (54A-2), completing said call request by connecting said first telephony device (54A-1) to said second telephony device (54A-3) using said call manager server.