Patent Application
20060045076
This application makes reference to, incorporates the same herein, and claims all benefits accruing under 35 U.S.C. §119 from an application for METHOD FOR CALL ROUTING OF VoIP GATEWAY AND SYSTEM THEREOF earlier filed in the Korean Intellectual Property Office on Aug. 31, 2004 and there duly assigned Serial No. 2004-69286.
1. Field of the Invention
The present invention relates to a Voice over Internet Protocol (VoIP) gateway, and more particularly, to a method and system for routing a call in a VoIP gateway in which when a caller tries making a VoIP call via an FXS (foreign exchange station), the VoIP gateway inserts a certain prefix (e.g., identifier) into a relevant FXS port to allow a called gateway to identify a caller based on the prefix, such that an FXO (foreign exchange office) port is allocated according to subscriber's priority.
2. Description of the Related Art
Presently, differentiated VoIP services are being provided depending on subscription grades which are marked differently to give priority to each subscriber.
For such differentiated services, different priority is given for use of a gateway port. A calling VoIP gateway, which interworks with an existing private branch exchange (PBX),cannot send caller information to a called gateway because the PBX adopts analog lines.
When terminal devices connected to the calling and called gateways are digital ones, it is possible to provide a differentiated service for each subscriber since caller ID is provided. However, it is not the case when the terminal devices of the respective gateways are analog ones.
In particular, since a PBX of a public switched telephone network (PSTN) type connected to the called gateway adopts an analog manner, it is impossible to be aware of the caller ID.
It is an object of the present invention to provide a system and method for routing a call in a VoIP gateway in which a prefix (e.g., identifier) is inserted according to a port to which a telephone terminal of a subscriber subscribing to a VoIP gateway is connected, and the inserted prefix is transmitted to a next VoIP gateway so that priority information of a caller is recognized, thereby providing a differentiated service for each subscriber.
In order to achieve the above object, the present invention provides a method for routing a call in a voice over IP (VoIP) gateway, including: requesting, by at least one caller, a VoIP call using their telephone terminal; inserting, by a calling gateway, a prefix for each foreign exchange station (FXS) port in response to the VoIP call request; routing, by the calling gateway, the VoIP call containing the prefix; identifying, by a called gateway, a caller based on the prefix contained in the received VoIP call; allocating, by the called gateway, a foreign exchange office (FXO) port for each identified caller; and routing, by the called gateway, the VoIP call to a destination telephone terminal via the allocated FXO port.
The method may further include removing the prefix, which is inserted by the calling gateway, when a relevant VoIP call is set by the called gateway to be routed via the relevant FXO port.
Allocating the FXO port for each caller may include allocating at least one FXO port for each subscription grade of callers according to a prescribed rule or policy. The method may include allocating the FXO port for each priority, the priority being given for each subscription grade of callers.
Inserting the prefix for each FXS includes including the prefix into a destination telephone number of a VoIP call incoming via each FXS port.
The method includes identifying the caller based on the prefix contained in the destination telephone number and routing the VoIP call to the FXO port allocated according to a subscription grade for each subscriber.
The present invention provides a system for routing a call in a VoIP gateway,including: a calling gateway for routing a VoIP call from users who subscribe to a VoIP service to a relevant destination, and including a certain prefix (e.g., identifier) into a destination telephone number according to a FXS port receiving a VoIP call to transmit it to a next stage; and a called gateway for identifying a caller based on the prefix received with the destination telephone number and routing the VoIP call to an FXS port upon receipt of the VoIP call from the calling gateway, the FXS port being previously set according to a grade of the identified caller.
The calling gateway may interface a caller terminal via the FXS port and insert a prescribed prefix into a destination telephone number for each FXS port to transmit it to a next stage.
The called gateway may discover an FXO port matched to a prefix value, which is received with the destination telephone number, by referring to an FXO port allocation table and route the VoIP call to a relevant FXO port.
The called gateway may remove the prefix, which is inserted by the calling gateway, when a relevant VoIP call is set by the called gateway to be routed via the relevant FXO port.
In the FXO port allocation table, at least one FXO port may be allocated for each grade of callers by a prescribed rule or policy. The FXO port may be allocated for each priority, the priority being given to each caller according to a subscriber line lease
A more complete appreciation of the present invention, and many of the attendant advantages thereof, will become readily apparent as the same becomes better understood by reference to the following detailed description when considered in conjunction with the accompanying drawings in which like reference symbols indicate the same or similar components, wherein:
a illustrates a process of inserting a prefix ina calling gateway according to an embodiment of the present invention;
b illustrates a process of selecting an FXO port using a prefix in a called gateway according to an embodiment of the present invention; and
c illustrates a process of connecting a VoIP call to a destination telephone through an FXO port according to an embodiment of the present invention.
Hereinafter, a prior art will be described with reference to the drawings.
Foreign exchange station (FXS)and foreign exchange office (FXO) interfaces, which are major components of the present invention, will be described before the configuration of the VoIP call routing system is described.
The FXS interface performs the same function as a PBX and is used for connection of a telephone, a facsimile, or a PBX trunk.
The FXS has the following major functions:
The FXO interface serves as a telephone and is used for connection to a local PBX's extension line or a PSTN line.
The FXO has the following major functions:
Referring to
The FXO must allocate a port so that a called gateway 40 routes an incoming call to a PSTN (K/P or PBX). Since there is no determination condition to apply a subscriber line lease condition or a call routing policy, an FXO port is allocated at random (S4).
Through such operation, a caller telephone is connected to a called telephone 50 corresponding to the number “70950000” (S5).
The detailed discussion on the called gateway 40 is given. Routing an incoming VoIP call to the PSTN requires allocation of the FXO port interfaced with the PBX.
However, a random FXO port can be allocated, which is not a specific FXO port, since there is no determination condition to apply a call routing policy or a subscriber line lease condition with respect to the incoming VoIP call.
This is because it is difficult for the called gateway 40 to identify a caller subscriber with only the destination number “70950000.”
Although the caller ID allows identifying the caller, it is not easily done in view of characteristics of the FXS port since the calling FXS employs analog lines, not digital lines.
Thus, it is required to allocate the FXO port at random due to difficulty in identifying the subscriber.
A conventional problem will be discussed under assumption that priority of line lease for each subscriber is set as in Table 1 below.
Even though a user or a subscriber A 11 having the highest priority is allocated a first FXO port as in Table 1, there is a possibility that other subscribers (users B 12, C 13, D 14, etc.) are using the first port. In this case, since the other users may occupy the FXO port of the subscriber A 11, the probability that an incoming call as well as an originating call fails is very high.
As a result, it is not assured that a high-quality service is provided to the subscriber A 11, who should be allocated a port more preferentially than other users.
This is because caller information is not provided to the called gateway, which makes it impossible to recognize caller's priority.
It is reasonable that a call for the subscriber (user C 13 or D 14) with a low priority is limited when a relevant FXO port is busy. However, in a conventional manner, when the subscriber with the low priority first requests a call and occupies a certain FXO port, a subscriber with a higher priority cannot be allocated a relevant port even when requesting a call. Accordingly, it is not assured that the subscriber receives a high quality service even though he requests the high quality service.
Referring to
That is, the calling gateway 200 inserts a distinguishable prefix for each port in a manner of inserting the prefix aa before the destination number of a call incoming from a first FXS port and the prefix bb before the destination number of a call incoming from a second FXS port. Thus, for the call incoming from the user A 110, the whole destination telephone number becomes “aa70950000” including the prefix.
An overall path of a VoIP call and a call routing system will be discussed below.
Referring to
Here, the prefix may be inserted before the telephone number depending on the intention of a network operator, or may be inserted into a field other than the telephone number. A more convenient method may be selected in view of management.
The prefix method of inserting the prefix before the telephone number will be discussed below with reference to both
a illustrates inserting a prefix in a calling gateway according to the present invention.
As shown in
The VoIP call is transmitted (S20) to a called gateway 400 over an IP network 300 with the prefix being inserted before the telephone number (S30).
The called gateway 400 must route the incoming call to a PSTN 410 which is an analog line, requiring a task allocating an FXO port, prior to the VoIP call being transmitted (S 50) to the called telephone 500.
By referring to a VoIP inbound routing table of Table 2, the called gateway 400 may allocate an FXO port based on information in a PSTN path field of an entry, which is matched to a prefix inserted before the destination telephone number (S40).
Here, the allocation of the FXO port is determined by a previously set rule or policy.
b illustrates setting an FXO port using a prefix in a called gateway according to the present invention.
Referring to
After allocating the FXO port, the called gateway 400 removes the prefix from the whole telephone number and transmits the VoIP call to the PSTN 410, as shown in
c illustrates a process of connecting a VoIP call to a destination telephone number via an FXO port according to the present invention. It shows that, after an FXO port is determined for a destination telephone number having a prefix inserted, only the destination telephone number is transmitted with the prefix being removed.
The PSTN 410 then routes the VoIP call incoming via the FXO port to a destination telephone 500 (S50).
The path to route the overall VoIP call is summarized as follows. The calling gateway inserts the prefix depending on the FXS port and the called gateway transmits the VoIP call via the FXO port allocated according to a previously set policy, thereby providing a stabilized service.
Currently, a different priority to use a port in the VoIP service is given according to a subscription grade for each subscriber. However, since there was no method capable of identifying the caller at the called VoIP gateway which interworks with an existing PBX, it was difficult to give a priority according to a subscription grade for each subscriber.
The present invention, however, assigns the prefix to the telephone number in a manner of inserting a prefix and the called gateway can identify the caller based on the prefix without using separate equipment. Thus, it is possible to provide a differentiated VoIP call service according to a subscription grade for each subscriber, which makes it possible for the subscriber to receive a more stabilized service.
Further, a service provider is capable of providing a differentiated service to subscribers according to the subscriber grade, thereby facilitating line management.
Although preferred embodiments of the present invention have been described, it will be understood by those skilled in the art that the present invention should not be limited to the described preferred embodiments. Rather, various changes and modifications can be made within the spirit and scope of the present invention, as defined by the following claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2004-0069286 | Aug 2004 | KR | national |
