1. Field of the Invention
The present invention relates to an Internet telephone apparatus that realizes a telephone call via the Internet, a adapter and a server that are used for the Internet telephone communication, an Internet telephone system, and a control method for the Internet telephone apparatus.
2. Description of Related Art
A conventional network that is used by so-called Internet telephone has been configured as follows.
Taking an Internet telephone system using H.323 protocol as an example, a managing server (referred to as gatekeeper) is provided within an Internet telephone network. This gatekeeper has functions to receive a phone number of a destination to be called, from each telephone in a unified way, to convert the phone number into a corresponding IP address, and to return the phone number back to the caller telephone.
When an operator inputs the desired phone number to be called, the number is called. When the telephone receives the IP address that corresponds to the telephone number from the gatekeeper, the telephone can access, based on the IP address, a telephone of the desired destination to be connected via the gatekeeper, or directly access the telephone without involving the gatekeeper. Accordingly, the telephone call can be made available via the Internet (see Related Art 1).
In addition, a router is normally involved between a gatekeeper and each telephone. A plurality of Internet telephones are connected to such a router, configuring a group in a network. Telephones within the same group have IP addresses having a common network address. In a normal corporate office setting, telephones within the same department are configured as the same group on the network.
FIG. 9(a) illustrates a network configuration of a commonly used Internet telephone system. In the network of FIG. 9(a), router A 902 and router B 903 are connected to management server 901. Internet telephones A1-A4 are connected to router A 902, configuring group (A), while Internet telephones B1-B4 are connected to router B 903, configuring group (B).
FIGS. 9(b) and (c) illustrate management charts that register telephone numbers assigned to each Internet telephone and IP addresses corresponding to the numbers. FIG. 9(b) and (c) respectively illustrate management charts of group (A) and group (B). In this example, telephone numbers are extension numbers used in a corporate setting.
As shown in FIG. 9(b), telephone numbers 1001-1004 are respectively assigned to Internet telephones (terminals) A1-A4, thereby having IP addresses of (192. 168. 1. 1)-(192. 168. 1. 4). Thus, network address (192. 168. 1) is commonly used for the above IP addresses of group (A) terminals.
As shown in FIG. 9(c), telephone numbers 2001-2004 are respectively assigned to Internet telephones (terminals) B1-B4, thereby having IP addresses of (192. 168. 2. 1)-(192. 168. 2. 4). Thus, network address (192. 168. 2) is commonly used for the above IP addresses of group (B) terminals.
[Related Art 1]
Japanese Patent Laid Open Publication 2002-101198 (Pages 4-5, FIG. 1)
The above described conventional art has the following shortcomings.
In a case where a call is place to a telephone in a department and the telephone is busy, the caller must hang up the phone and dial another number of a telephone, which is in close proximity to the unavailable telephone, if it is for an urgent matter. Therefore, such a calling operation has been very cumbersome to the caller.
The above network configuration is further described using the example of terminal A1 placing a call to terminal B1. FIG. 10 is a sequence chart illustrating an operation of a conventional Internet telephone system.
As shown in FIG. 10, when a call is placed from terminal A1 to terminal B1, the caller first input telephone number (2001) of terminal B1. Upon receiving the telephone number input, terminal A1 requests for an IP address of terminal B1 from server 901. Then, server 901 provides the IP address of terminal B1. Based on the provided IP address, terminal A1 places a call to terminal B1.
In this example, terminal B1 is busy, thus the connection to terminal B1 is unsuccessful and terminal A1 sounds a busy tone. Upon confirming the busy tone, the caller hangs up the telephone first, and inputs telephone number (2002) of terminal B2. Similar to the situation of calling terminal B1, terminal B2 is called when terminal A1 receives an IP address of terminal B2 from server 901.
In this example, terminal B2 is also busy, thus the connection to terminal B2 is unsuccessful and terminal A1 sounds a busy tone. Upon confirming the busy tone, the caller hangs up the telephone, and inputs telephone number (2003) of terminal B3. Similar to calling terminal B1 and terminal B2, terminal B3 is called when terminal A1 receives an IP address of terminal B3 from server 901.
In this example, terminal B3 is not busy, thus the connection between terminals A1 and B3 is successful. Therefore, a message to the operator of terminal B1 is delivered to the operator of terminal B3. As described above, when one terminal in a department is busy, the operator must dial another number of an adjacent terminal.