Virtual PBX Based on SIP and Feature Servers

1 . A hierarchical internet telephony system comprising:

a higher tier internet telephony feature server coupled to a communication network, the multiple user internet telephony feature server directing telephone calls for a plurality of users; and

a plurality of lower tier internet telephony feature servers in communication with the higher tier internet telephone feature server over the communication network, each lower tier internet telephony feature server directing telephone calls for an individual user, wherein the higher tier internet telephony feature server is configurable to direct telephone calls to the lower tier internet telephony feature servers, and wherein each lower tier internet telephony feature server is separately configurable to direct telephone calls forwarded to it by the higher tier internet telephony feature server.

2 . A hierarchical internet telephony system according to claim 1 , wherein each lower tier internet telephony feature server is configured by its respective user to operate with the higher tier internet telephony feature server, and wherein the higher tier internet telephony feature server is configured to either reject telephone calls for a particular lower tier internet telephony feature server or accept and forward telephone calls for the lower tier internet telephony feature server.

3 . A hierarchical internet telephony system according to claim 1 , wherein telephone calls are forwarded strictly according to the hierarchy.

4 . A hierarchical internet telephony system according to claim 1 , wherein telephone calls are permitted to be forwarded among peer lower tier internet telephony feature servers.

5 . A hierarchical internet telephony system according to claim 1 , wherein each internet telephony feature server comprises:

a network interface, couplable to a communication network, for sending and receiving internet telephony signals over the communication network; and

a controller operably coupled to the network interface for handling telephone calls received as internet telephony signals over the network interface.

6 . A hierarchical internet telephony system according to claim 5 , wherein each internet telephony feature server further comprises:

a web-based management interface, accessible through the network interface, through which the controller can be configured.

7 . A hierarchical internet telephony system according to claim 5 , wherein each lower tier internet telephony feature server further comprises a telephone interface, couplable to a telephone device, for sending telephone control signals to the telephone device and receiving telephone control signals from the telephone device, wherein the controller is operably coupled to direct telephone calls intended for the telephone device and to manage telephone services on behalf of the telephone device based on the telephone control signals received from the telephone device over the telephone interface.

8 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to ring the telephone device over the telephone interface upon receiving a telephone call over the network interface.

9 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to ring at least one other telephone device over the network interface simultaneously with ringing the telephone device over the telephone interface.

10 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to ring at least one other telephone device over the network interface if the telephone device is not answered within a predetermined time.

11 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to forward a telephone call to another telephone device over the network interface in lieu of ringing the telephone device over the telephone network upon receiving a telephone call over the network interface.

12 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to generate a call waiting signal to the telephone device over the telephone interface upon receiving a telephone call over the network interface.

13 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to interrupt an existing telephone call to the telephone device with a new telephone call received over the network interface.

13 . A hierarchical internet telephony system according to claim 7 , wherein the controller is configurable to permit one-way communication from a new telephone call received over the network interface to the telephone device over the telephone network.

14 . A hierarchical internet telephony system according to claim 5 , wherein the controller is configurable to provide at least one of the following services:

central number and hunting assignment;

call holding;

call transfer;

simultaneous ring;

interrupt;

conference call.

15 . A hierarchical internet telephony system according to claim 5 , wherein the controller is configurable to direct telephone calls based on time of day.

16 . A hierarchical internet telephony system according to claim 5 , wherein each lower tier internet telephony feature server further comprises at least one of a microphone and a speaker.

17 . A hierarchical internet telephony system according to claim 1 , wherein each of the internet telephony feature servers operates without assignment of an explicit global network address.

18 . A hierarchical internet telephony system according to claim 1 , wherein the internet telephone feature servers intercommunicate using a network protocol.

19 . A hierarchical internet telephony system according to claim 18 , wherein the network protocol is the Internet Protocol (IP).

20 . A hierarchical internet telephony system according to claim 1 , wherein at least one of the internet telephony feature servers acts as a SIP proxy server.

21 . A hierarchical internet telephony system according to claim 1 , wherein at least one of the internet telephony feature servers acts as a SIP redirect server.