# Patent

## Title
Method of operating a virtual private network

## Abstract

A method of operating a virtual private network includes the steps of: (a) dialing a custom number; (b) receiving the custom number at a switch (20) of a first carrier; (c) routing the call to a switch (18) of a second carrier based on having received the custom number; and (d) when the call to the switch (18) of the second carrier includes a plain old telephone number translation of the customer number, routing the call over the second carrier to a service switching point (26) of a third carrier.

## Background
RELATED APPLICATIONS
This patent arises from a continuation of U.S. patent application Ser. No. 10/795,767 which was filed on Mar. 8, 2004 now U.S. Pat. No. 7,190,780 and which is a continuation of U.S. patent application Ser. No. 09/599,843 which was filed on Jun. 22, 2000, issued as U.S. Pat. No. 6,741,693 and which is a continuation of U.S. patent application Ser. No. 08/969,598 which was filed on Nov. 13, 1997 and issued as U.S. Pat. No. 6,141,409.


FIELD OF THE INVENTION
The present invention relates generally to the field of telecommuncations and more particularly to a method of operating a virtual private network.
BACKGROUND OF THE INVENTION
Companies often use abbreviated dialing plans at a location. This allows the user to dial an internal number (abbreviated number) to reach other people within the same location. Virtual private networks (VPN) have allowed companies having several locations in the same Local Access and Transport Area (LATA) to share the abbreviated dialing plan. The VPN allows the various locations of a company to also provide other features such as call transfer, multiway calling, and call forwarding. A company that decides to use a VPN can provide all these features without buying expensive Private Branch Exchanges (PBX) for each location and without having to lease lines between each of the locations. This has provided the customer with flexibility and cost savings over setting up a standard private network. Unfortunately, companies that have locations in two or more LATAs could not use a VPN to provide these services. This is because the present regulatory environment requires two or more carriers when connecting two separate LATAs using the Public Switched Telephone Network (PSTN). As a result, these customers were required to lease lines between the LATAs and use access codes for the various locations, to obtain services similar to a VPN.
Thus there exists a need for a method of operating a virtual private network that works across several LATAs and several service providers.
SUMMARY OF THE INVENTION
A method of operating a virtual private network that overcomes these and other problems includes the steps of: (a) dialing a custom number; (b) receiving the custom number at a switch of a first carrier; (c) routing the call to a switch of a second carrier based on having received the custom number; and (d) when the call to the switch of the second carrier includes a plain old telephone number translation of the customer number, routing the call over the second carrier to a service switching point of a third carrier.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a schematic diagram of an embodiment of a virtual private network;
FIG. 2 is a schematic diagram of an embodiment of a virtual private network;
FIG. 3 is a flow chart of an embodiment of the steps used in operating a virtual private network; and
FIG. 4 is a flow chart of an embodiment of the steps used in operating a virtual private network.



DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematic diagram of an embodiment of a virtual private network 10. In this embodiment, the provider of the virtual private network 10 is not the local provider in LATA-1, LATA-2 or LATA-3. When a customer dials an on-network telephone number from a telephone 12 in LATA-1 of an originating carrier, a service switching point (SSP-A) 14 receives the dialed number. A service switching point is an intelligent network switch. The on-network number can be 4-11 digit number and the customer does not have to dial an access code before dialing the on-network number. The SSP-A 14 performs a number identifier operation to determine if the call should be routed over a private line 16 to an intermediate carrier switch 18. The number identification operation is performed in one embodiment by comparing the received number with a predefined set of numbers. In one embodiment, the predefined set of numbers includes all the on-network telephone numbers for a particular virtual private network. When the number belongs to the predefined set of numbers, then the call is routed to the intermediate carrier switch 18. In one embodiment the intermediate carrier switch 18 is an interexchange carrier (IXC) point of presence (POP) switch. The intermediate carrier switch 18 is connected to other SSPs, such as SSP-B 20.
The intermediate carrier switch 18 is connected by an intelligent network 22 to a network carrier Service Control Point (SCP) 24. A SCP provides a number of intelligent functions, including routing and billing information for calls to a SSP. When the intermediate carrier switch 18 receives the call over the private line 16, it encounters a custom dialing plan trigger. The intermediate carrier switch 18 then sends a query over the intelligent network 22 to the SCP 24. The query (information analyzed query) will include at least the calling party directory number (calling party telephone number) and the dialed digits (on-network telephone number). The SCP 24 will analyze the query and return a message including routing instructions. The message will include at least the plain old telephone number translation (directory number) of the on-network number. In another embodiment the message will include a signaling indication and may also include primary trunk group, secondary trunk group, primary carrier and alternate carrier. The primary trunk group defines a particular line (private line) over which the call should be routed if possible. The primary carrier defines a preferred interexchange carrier over which the call should be routed if possible.
Upon receiving the message and routing instructions the intermediate switch 18 routes the call based on the routing instructions. if the customer at telephone 12 dialed an on-network number of a facility connected to SSP-E 26 (terminating service switching point) in LATA-3, the call would be routed through the intermediate carrier's network 28 to an intermediate switch 30. When the message includes the signaling indication, the call is routed by the intermediate switch to the SSP-E 26 over a private line 32. The SSP-E 26 then routes the call to the called customer.
When the message does not include the signaling indication, the intermediate switch 30 triggers on the plain old telephone number. The intermediate switch 30 sends a query (routing query) to a second service control point (SCP) 34. The routing query includes the plain old telephone number and the calling telephone number. The SCP 34 then determines if the plain old telephone number and the calling telephone number belong to the same virtual private network. When the plain old telephone number and the calling telephone number belong to the same virtual private network, then the call is routed over a private line 32. When the plain old telephone number and the calling telephone number do not belong to the same virtual private network, the call is routed over public facilities to SSP-E.
If the customer at telephone 12 dialed an on-network number of a facility connected to SSP-C 36 or SSP-D 38 in LATA-2, the intermediate switch 18 would route the call through the intermediate carrier's network 28 to an intermediate switch 40. In one embodiment the intermediate carrier's network is a private line connecting the switches 18, 40. The intermediate switch 40 in one embodiment then routes the call over public facilities to SSP-C 36 or SSP-D 38. In another embodiment, the signaling indication tells the switch 40 to route the call over private facilities 42, 44 to SSP-C 36 or SSP-D 38. As explained above the intermediate switch 40, in one embodiment, triggers on the call and sends a query to the SCP 24 to determine if the plain old telephone number and the calling number are part of the same virtual private network. When the numbers are part of the same virtual private network, the intermediate switch 40 routes the call over private lines 42, 44. Using the method described above, a virtual private network connecting facilities connected to SSP-A 14, SSP-B 20, SSP-C 36, SSP-D 38, SSP-E 26 has been described. The virtual private network works across multiple LATAs and multiple service providers.
FIG. 2 shows a schematic diagram of another embodiment of a virtual private network 50. In this case the call originates from LATA-1 having local exchange carrier (LEC-1). In this embodiment, the network carrier providing the virtual private network service is the same as LEC-1. A user dials a number (on-network number) on telephone 52 to initiate a call. SSP-A 54 of the first carrier (LEC-1) receives the number. The SSP-A 54 triggers on the number and sends a query to the network service control point (SCP) 55 over an intelligent network 56. The query includes the number dialed. The SCP 55 responds with a plain old telephone number translation of the number and a signaling indication in one embodiment. The SSP-A 54 then routes the call over a private line 58 to a switch 60 of an intermediate carrier (second carrier), when the call is directed to facilities connected to either SSP-E 62 in LATA-2 or SSP-F 64 in LATA-3. When the call is directed to facilities in LATA-1 (first local access and transport area), such as SSP-B 66 or SSP-C 68, SSP-A 54 in one embodiment contains sufficient information to route the call over private facilities 70, 73 to SSP-B 68 or SSP-C 68. Note that SSP-B and SSP-C 68 are connected by private facilities 74. In another embodiment, SSP-A 54 sends a query to SCP 55 and then routes the call over public or private facilities to SSP-B 66 or SSP-C 68.
The switch 60 routes the call based on the plain old telephone number (POTS) through the second carrier to a switch 76, when the call is to facilities connected to SSP-E 62. When the SCP 55 included a signaling indication in its routing message, then the switch 76 routes the call over private facilities 78 to SSP-E 62. When the SCP 55 did not include the signaling indication in its routing message, the switch 76 routes the call over public facilities to SSP-E 62 based on the POTS translation of the dialed number.
When the call is directed to a facility connected to SSP-F 64, the switch 60 routes the call through the second carrier's network to a switch 80. In one embodiment, the switch 60 is connected to switch 80 by a private line 82. In one embodiment, the switch 80 routes the call over public facilities to SSP-F 64, based upon the POTS number. In another embodiment the switch 80 routes the call over private facilities 84 to SSP-F, based upon the signaling indication. In yet another embodiment, the switch 80 routes the call over private facilities 84 after sending a query to SCP 55. The SCP 55 determines that the calling party and called party are part of the same virtual private network.
FIG. 3 is a flow chart of an embodiment of the steps in used in operating a virtual private network. The process starts, step 100, by a user dialing a number at step 102. The number is received at an switch at step 104 At step 106 it is determined if the dialed number belongs to predefined set of numbers. When the number does not belong to the predefined set of numbers (predetermined group of numbers), then other processing is performed at step 108. When the number does belong to the predefined set of numbers (predetermined set), the call is routed over a private line at step 110. At step 112, a custom dialing plan (CDP) trigger is performed at an intermediate carrier switch. The intermediate carrier switch sends a query to a network SCP at step 114. At step 116, the switch receives a message (response) including routing instructions. The call is routed using the routing instructions at step 118, which ends the process at step 120.
FIG. 4 is a flow chart of another embodiment of the steps in used in operating a virtual private network. The process starts, step 130, when a customer number is dialed at step 132. A custom number is a number that does not conform to a standard number or dialing plan (e.g., the North American Numbering Plan). The customer number is received at a first carrier's switch at step 134. The SSP routes the call to a switch at a second carrier at step 136. The switch determines if the call includes a plain old telephone number translation of the custom number at step 138. When the call does include the a plain old telephone (POTS) number translation of the custom number, the call is routed to a SSP of a third carrier (terminating carrier) based on the POTS number at step 146, which ends the process at step 142.
When the call does not include the POTS number translation of the custom number, the switch of the second carrier sends a query to a network SCP at step 144. Note that the network SCP can be part of the first carrier, second carrier, third carrier or part of a separate carrier. The switch then receives routing instructions including the POTS number translation of the custom number at step 146. Based on the POTS number the call is routed to a second switch of the second carrier at step 148. Next, it is determined if the call includes a signaling indicator (received signaling indicator) at step 150. When the signaling indicator is included, the call is routed over a private line at step 152. The call is connected to the SSP of the third carrier at step 140, which ends the process at step 142.
When the signaling indicator is not included, a query is sent to a second SCP to determine if the POTS number and the originating number are part of the same virtual private network at step 154. When the POTS number and the originating number are part of the same virtual private network, the call is routed over a private line at step 152. The call is connected to the SSP of the third carrier at step 140, which ends the process at step 142. When the POTS number and the originating number are not part of the same virtual private network, the call is routed over the public network at step 156. The call is received at the SSP in the third carrier at step 140, which ends the process at step 142.
Thus there has been described a method of operating a virtual private network works across several LATAs and several service providers. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alterations, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alterations, modifications, and variations in the appended claims.

## Claims

1. A method of operating a virtual private network, comprising:
receiving a dialed number at an originating carrier;
performing a number identifier operation based on the dialed number without contacting a service control point to determining whether a call should be routed on a private line to an intermediate carrier switch;
when the call is routed to the intermediate carrier switch over the private line, sending a query including the dialed number from the intermediate carrier switch to a network carrier service control point;
receiving a message containing a routing instruction including a plain old telephone number translation of the number; and
routing the call based on the routing instruction.

2. The method of claim 1, further comprising:
receiving the call at an intermediate switch;
routing the call to a terminating service switching point.

3. The method of claim 2, wherein routing the call to the terminating service switching point comprises routing the call over a private line.

4. The method of claim 2, wherein routing the call to the terminating service switching point further comprises:
triggering on the plain old telephone number at the intermediate switch;
sending a routing query to a second service control point;
checking if a calling telephone number and the plain old telephone number belong to a same private network;
when the calling telephone number and the plain old telephone number belong to the same private network, routing the call from the intermediate switch over a private line to the terminating service switching point.

5. The method of claim 1, wherein the dialed number has less than seven digits.

6. The method of claim 1, wherein performing the number identifier operation based on the dialed number without contacting a service control point comprises comparing the dialed number to a set of numbers.

7. A method of operating a virtual private network, comprising:
receiving a number to initiate a call at a first local access and transport area (LATA) of a first carrier;
performing a number identifier operation based on the dialed number without contacting a service control point to determining whether a call should be routed on a private line to a switch of an intermediate carrier switch;
routing the call over the private line to the switch of the intermediate carrier; and
routing the call over a private line from the intermediate carrier to a terminating carrier in a second LATA.

8. The method of claim 7, wherein routing the call over the private line from the intermediate carrier to the service switching point of the terminating carrier further comprises:
determining whether received routing instructions include a signaling indicator; and
when the routing instructions include the signaling indicator, routing the call over the private line.

9. The method of claim 7, wherein routing the call over the private line from the intermediate carrier to the terminating carrier further comprises:
sending a query to a service control point;
determining whether a plain old telephone number corresponding to the dialed number and a calling party telephone number belong to a virtual private network; and
when the plain old telephone number and the calling party telephone number belong to the virtual private network, routing the call over the private line.

10. The method of claim 7, wherein the second LATA is of a second carrier and the intermediate switch is of a third carrier.

11. A method of operating a virtual operating network, comprising:
receiving a custom number at a first switch of a first carrier;
performing a number identifier operation at the switch of the first carrier based on the dialed number without contacting a service control point to determining whether a call should be routed on a private line;
routing the call on the private line; and
when the call reaches a second switch of a second carrier with a plain old telephone number translation of the custom number, routing the call to a service switching point of a third carrier.

12. The method of claim 11, further comprising:
when the call reaches the second switch of the second carrier without the plain old telephone number translation of the custom number:
sending a query to a network service control point; and
receiving a routing instruction including the plain old telephone number translation of the custom number.

13. The method of claim 12, further comprising routing the call based on the plain old telephone number to a third switch of the second carrier; wherein, when the call is received at the third switch with a signaling indicator, the call is routed from the third switch over a private line to the service switch point of the third carrier.

14. The method of claim 13, further comprising:
when the call is received at the third switch without the signaling indicator, determining if a calling number and the plain old telephone number belong to a private network without contacting a service control point; and routing the call from the third switch over the private line to the service switch point of the third carrier when the calling number and the plain old telephone number belong to the private network.

15. The method of claim 11, wherein the custom number includes less than seven digits.