System and method for establishing a communication connection
View Patent ↗Narrowband subscriber terminals ( 40,52,58 ) of different narrowband networks are interconnected via a broadband network ( 48 ) that supports dissimilar signaling protocols to those maintained on the respective narrowband networks ( 40,52,58 ). A call server in a first narrowband network ( 40 ), in response to a call ( 100 ) from a first subscriber terminal ( 12 ) to a second subscriber terminal ( 68 ) in a second but different narrowband network ( 52 ), selects a phantom trunk ( 202 ) between the two networks. The phantom trunk has a unique circuit identity, which circuit identify is used in a first instance to relay to the second network an address of the second subscriber terminal ( 68 ). Then, in a second instance, the unique circuit identify is used to relay to the second network an address of the first subscriber terminal ( 68 ). By recognizing that two connection requests have been received at opposite ends of the same phantom trunk, a processor in the second network is able to determine that a direct connection between the first and second subscriber terminals is required through the broadband network ( 48 ).
1. A method of establishing a call between a first narrowband switch and a second narrowband switch across a broadband network connecting said first and second narrowband switches, the first and second narrowband switches also being connected by a narrowband signalling link, the method comprising the steps of:
a. receiving a call request at the first narrowband switch;
b. sending call signalling data to the second narrowband switch over the narrowband signalling link;
c. at the first narrowband switch establishing via a call server of said first narrowband switch a first phantom trunk to the second narrowband switch over the narrowband signalling link;
d. at the second narrowband switch establishing via a call server of said second narrowband switch a second phantom trunk to the first narrowband switch over the narrowband signalling link;
e. at one of said first and second narrowband switches determining from said first and second phantom trunks a connection to be established over said broadband network between said first and second narrowband switches; and
f. establishing said connection between the first and second narrowband switches over the broadband network to thereby establish the call over the broadband network between the first and second narrowband switches.
2. The method of claim 1 , wherein the step of establishing the first phantom trunk comprises establishing the first phantom trunk between a calling subscriber terminal connected to the first narrowband switch and the second narrowband switch.
3. The method of claim 2 , wherein the step of establishing the second phantom trunk comprises establishing the second phantom trunk between a called subscriber terminal connected to the second narrowband switch and the first narrowband switch.
4. The method of claim 3 , wherein the step of establishing the first phantom trunk includes selecting a said call server at the first narrowband switch an available phantom trunk on said narrowband signalling link that connects a narrowband trunk and the second narrowband switch, said narrowband trunk comprising a trunk assigned to a connection between the calling subscriber terminal and the first narrowband switch.
5. The method of claim 3 , wherein the step of establishing the second phantom trunk includes sending call signalling data from the first narrowband switch over the narrowband signalling link to the second narrowband switch comprising a circuit identification code ‘CIC’ for the first phantom trunk and a telephone number of the called subscriber terminal.
6. The method of claim 1 , wherein the step of sending call signalling data comprises sending SS7 signalling data.
7. The method of claim 1 , further comprising receiving the call signalling data at the second narrowband switch unchanged.
8. The method of claim 1 , further comprising receiving the call signalling data at the second narrowband switch unchanged irrespective of how the call is established.
9. The method of claim 1 , wherein the step of establishing the call comprises establishing the call without making any change to the content or format of the call.
10. The method of claim 1 , further comprising carrying out the steps of establishing the first and second phantom trunks in respective connection brokers of the first and second narrowband switches.
11. A communication system having a broadband network and a plurality of narrowband switches between which calls can be established, said plurality of narrowband switches being connected by said broadband network and a narrowband signalling link, the system comprising:
a. a first narrowband switch;
b. a second narrowband switch;
c. a call signalling path on said narrowband signalling link for passing call signalling data from the first narrowband switch to the second narrowband switch;
d. a first call server at said first narrowband switch for establishing a first phantom trunk to the second narrowband switch over the narrowband signalling link;
e. a second call server at said second narrowband switch for establishing a second phantom trunk to the first narrowband switch over the narrowband signalling link;
f. one of said first and second narrowband switches being arranged to determine from said first and second phantom trunks a connection to be established over said broadband network between said first and second narrowband switches; and to establish said connection between the first and second narrowband switches over the broadband network to thereby establish a call over the broadband network between the first and second narrowband switches.
12. The system of claim 11 , wherein the first call server is arranged to establish the first phantom trunk between a calling subscriber terminal connected to the first narrowband switch and the second narrowband switch.
13. The system of claim 12 , wherein the second call server is arranged to establish the second phantom trunk between a called subscriber terminal connected to the second narrowband switch and the first narrowband switch.
14. The system of claim 13 , wherein the first call server is arranged to select at the first narrowband switch an available phantom trunk on said narrowband signalling link that connects a narrowband trunk and the second narrowband switch, said narrowband trunk comprising a trunk assigned to a connection between the calling subscriber terminal and the first narrowband switch.
15. The system of claim 13 , wherein the second call server is arranged to send call signalling data from the first narrowband switch over the narrowband signalling link to the second narrowband switch comprising a circuit identification code ‘CIC’ for the first phantom trunk and a telephone number of the called subscriber terminal.
16. The system of claim 11 , wherein the signalling data is SS7 signalling data.
17. The system of claim 11 , wherein the call signalling data is received at the second narrowband switch unchanged from its starting state.
18. The system of claim 11 , wherein the call signalling data is received at the second narrowband switch unchanged from its starting state irrespective of how the call is established.
19. The system of claim 11 , wherein the call is established without making any changes to the content or format of the call.
20. The system of claim 11 , wherein the establishment of the first and second phantom trunks are made by respective connection brokers of the first and second narrowband switches.