JP3749285B2 - Wireless base station, portable communication terminal, and mobile communication system - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a radio base station in a mobile communication system, and more particularly, to a calling voice mail system that stores items to be transmitted from a portable communication terminal to a partner terminal, and thereafter sends a substitute to the partner terminal .
[0002]
[Prior art]
Conventionally, it performs proxy reception to a portable communication terminal that is in a state where it is not possible to receive a call during a call or due to the absence of an operator, and then transmits the proxy reception contents to the other party and completes the transmission A voice mail method for notifying a reception requester and confirming delivery is known from Japanese Patent Laid-Open No. 7-30967.
[0003]
In this technology, as shown in FIG. 13, a plurality of portable terminals 47 and a plurality of radio base stations 46 are provided in a service area 49, and a terminal 48 is located outside the service area 49. .
The plurality of radio base stations 46 are connected to the fixed network terminal 42 via the radio telephone exchange 43, and the exchange 43 is connected to a database 45 for recording various data of the plurality of base stations 46 and an alternate reception database 44. ing.
[0004]
[Problems to be solved by the invention]
In the above prior art, in the database 44 connected to the radio telephone exchange 43 connected to a plurality of radio base stations, the reception data received by all of the base stations, for example, the caller name, the caller communication Since data such as the destination telephone number, call time, and messages are recorded, the amount of recording memory increases, the facility space increases, and if this switch breaks down, all substitutions are made. The use of received data became impossible, and the communication traffic opportunity increased in the database, and advanced technology was required to cope with it.
[0005]
In addition, the above-described prior art has a problem that since the base station and the terminal are communicated by radio, the substitute reception data becomes unclear due to radio wave interference, a decrease in the transmission output of the terminal, and the like.
[0006]
In view of the circumstances described above, the object of the present invention is to make the received data unclear due to radio interference, a decrease in the transmission output of the portable communication terminal, etc. without increasing the capacity of the voice mail (alternate reception) database. It is an object of the present invention to provide a radio base station, a portable communication terminal, and a mobile communication system that can prevent this problem .
[0007]
[Means for Solving the Problems]
According to the present invention, in a radio base station that relays a call from a portable communication terminal to a partner terminal, a voice mail database that stores transmission items from the portable communication terminal to the partner terminal, and the transmission A calling voice mail means for proxying the matter to the destination terminal;
Wherein when receiving a location registration request signal from the portable communication terminal, wherein when the transmission output level transmission output level by measuring the portable communication terminal is not in a predetermined range, and transmits a control signal to said mobile communication terminal wherein possess a terminal output level adjusting means for instructing an adjustment of the transmit power level to the portable communication terminal, and a memory means for storing the transmission output level when the transmitting the control signal,
Upon receipt of a voice mail transmission item from the portable communication terminal to the destination terminal and designation of the calling time, etc., it is stored in the voice mail database and designated by the calling voice mail means. it characterized in that a call transfer matters to the destination terminal.
[0008]
The voice mail database is shared with a database for call memos that stores call contents between portable communication terminals ,
When a call between the portable communication terminal and the partner terminal is started, recording of the call content starts in the database, and after the call ends, when receiving a signal requesting storage of the call content from the portable communication terminal, Preferably, the call content is stored with a storage number, and the storage number is notified to the portable communication terminal. The wireless base station transmits the control signal and then transmits the portable communication terminal. If the transmission output level of the terminal is not improved, output level adjustment impossible notification means for transmitting an output level adjustment impossible notification to the portable communication terminal is provided. In addition, after transmitting the transmission item to the counterpart terminal, the radio base station does not receive an erasure signal instructing erasure of the transmission item from the portable communication terminal. It is preferable to provide an erasing unit for erasing the transmission matter.
[0009]
Further, according to the present invention, the portable communication terminal comprises: an output level adjusting unit that adjusts a transmission output level when receiving the control signal; a warning unit that gives a warning when receiving the notification that the output level cannot be adjusted; and the voice mail The mobile communication system includes a plurality of radio base stations and a plurality of portable communication terminals.
[0010]
[Action]
The present invention provides a memory in a radio base station that relays a call from a portable communication terminal to a partner terminal, and provides a database for recording substitution reception data in the memory, and the database includes the database from the portable communication terminal. A matter to be transmitted to the counterpart terminal is temporarily stored, and thereafter, the proxy transmission is performed from the base station to the counterpart terminal.
[0011]
Since there is a voice mail database for storing the transmission items for each radio base station, the amount of recording memory is increased, the space of the facility is not enlarged, even when a failure occurs, It does not affect the reception memory of other radio base stations, and the use of all the reception data is not disabled.
In addition, since each base station has an alternate reception database, there are few opportunities for communication traffic in the database.
[0012]
In addition, when the voice mail database is configured to be shared with a call memo database for storing call contents between terminals, it is more efficient in a small-capacity database provided with a single database and an empty space. Data management.
[0013]
Further, the wireless base station measures the transmission output level of the portable communication terminal, and when the transmission output level is not within a predetermined range, transmits a control signal to set the transmission output level of the portable communication terminal. A terminal output level arithmetic circuit to be adjusted is provided, and the terminal is provided with an output level adjustment circuit, and the transmission output of the terminal can be adjusted by the control signal of the base station, and transmission can be performed at an optimum level. The reception data is not obscured due to radio interference, a decrease in the transmission output of the terminal, or the like.
[0014]
If the transmission output of the terminal is not improved even when the control signal is transmitted, an output level adjustment impossibility notification is transmitted to the terminal, and the terminal display unit is blinked.
Further, at the time of calling, a warning signal for voice warning is transmitted at the terminal.
[0015]
In addition, when the destination terminal is unable to receive a call, a voice mail acceptance signal is transmitted from the base station, and a message or the like is transmitted from the terminal in response thereto. The terminal has the calling voice mail function. Since the key means for requesting is provided, voice mail can be performed by the key means together with the calling signal regardless of whether or not the destination terminal is disabled.
[0016]
【Example】
Hereinafter, the present invention will be described in detail with reference to the embodiments shown in the drawings. However, the dimensions, materials, shapes, relative positions, and the like of the components described in this embodiment are merely illustrative examples and not intended to limit the scope of the present invention unless otherwise specified. Absent.
[0017]
FIG. 1 is a schematic configuration diagram of a mobile communication system used in an embodiment of the present invention, FIG. 2 is an embodiment diagram showing an external configuration of a communication terminal used in the embodiment of the present invention, and FIG. FIG. 4 is a circuit block diagram of the radio base station, FIG. 5 is a diagram illustrating the operation procedure of the output level adjustment function of the terminal, and FIG. 6 is a diagram illustrating the procedure of the voice mail function. 7 is an explanatory diagram of the first half of the operation procedure of the call memo function, and FIG. 8 is an explanatory diagram of the second half of the operation procedure of the call memo function.
[0018]
In FIG. 1, a plurality of wireless base stations 20A, 20B, and 20C are wired to a communication carrier network 41 that is wired to each telephone terminal, and these wireless base stations are connected to a plurality of terminals 1A ′, 1A, 1B or the like can be wirelessly communicated, and is connected via a network 41 to a data management center 40 that stores and manages various data of the base station and the terminal.
[0019]
The base station 20 is provided with a memory 31A (31B) for voice mail (e-mail) and call memo, which will be described later, and a terminal 1A and a terminal 1A ′ which are different from the base station 20 in distance from each other. A mechanism (not shown) is provided for measuring and adjusting the output level to a predetermined level.
[0020]
FIG. 2 is a diagram showing an external configuration of the communication terminal used in the embodiment of the present invention. In the figure, the main body 1 of the terminal has a thin and substantially rectangular shape, and a telescopic antenna 2 is erected at the upper left corner of the upper edge and is automatically closed to the left side surface, thereby automatically requesting the location registration of the terminal. A power switch 10 for transmitting radio waves is provided.
[0021]
On the front surface of the terminal 1, a speaker unit 3 is provided above, and a speaker 9 that rings a ringing tone is provided in the vicinity thereof. Underneath, a display for visually displaying various information including the telephone number of the other party by operating a numeric keypad. A key operation input unit 5 comprising a call switch 5a for transmitting a call signal, an on-hook switch 5b, a switch 5c for designating a call destination on an extension, and a numeric keypad operation unit 6 therebelow. Furthermore, a number registration request key 7a for requesting telephone number registration, an external terminal / slave unit switching key 7b, and other function keys 7 for realizing shortening, holding, and other various functions are arranged below that. Below that, a transmitter 8 is incorporated.
[0022]
FIG. 3 is a configuration diagram illustrating a circuit block of the communication terminal. The communication terminal 1 is provided with a CPU (Central Processing Element) 11 that controls various control operations on the terminal side. The CPU 11 includes the antenna 2, the speaker 3 as a receiver, and the transmitter. A wireless communication circuit 14 including a microphone 8 is connected, and performs a predetermined registration request / call / incoming / call operation while exchanging data with the CPU 11.
[0023]
Further, the CPU 11 is provided with a memory 12, which temporarily stores a terminal output control signal, an output level state, a call memo storage number, and the like received from the radio base station 20, which will be described later, received via the communication circuit 14. To do.
The CPU 11 is connected to a terminal output level adjustment circuit 18 by the terminal output control signal, and the circuit 18 adjusts the output level to a predetermined range.
[0024]
Further, the CPU 11 has the above-described key operation input unit 5, an input / output device 17 constituted by a numeric keypad operation unit 6, function keys, and the like, input information, terminal output level warning, etc. by key operation of the input / output device 17. Is connected to the display unit 4.
A ROM 13 connected to the CPU 11 stores a program for processing registration, transmission / reception, and other functions in a predetermined flow.
The RAM 15 connected to the CPU 11 stores a manufacturing number and the like in advance at the time of manufacturing.
The ringing tone generation circuit 16 is a circuit that receives a call via the communication circuit 14 and generates a ringing tone. The ringing tone generation circuit 16 rings the connected sound generator 9.
[0025]
FIG. 4 is a circuit block diagram of the radio base station. The radio base station 20 is provided with a central processing unit (CPU) 21 that controls various control operations of the base station. A radio communication circuit 24 including an antenna 22 is connected to the CPU 21. Wireless communication is made with the terminal 1 while exchanging data between them.
The CPU 21 is connected to a telephone line interface unit 25 connected to the operator network 41 (FIG. 1), and communicates with a telephone terminal and other data management center 40.
[0026]
The CPU 21 is connected to a data transmitting / receiving unit 26 for recording various data received from the telephone line interface unit 25 in the information data memory 28.
The data in the information data memory 28 is configured to be able to be searched and listened to from the terminal via the communication unit 24, the data transmission / reception unit 27, and the information data search circuit 27.
A ROM 23 connected to the CPU 21 stores a program for processing transmission / reception and other functions in a predetermined flow.
[0027]
Further, a memory 31 is connected to the data transmitting / receiving unit 27, and the memory 31 records an e-mail message and a call memo of the communication terminal 1 received via the wireless communication circuit 24.
The terminal output level calculation circuit 30 connected to the information data memory 28 and the data transmission / reception unit 27 measures the output level of the location registration information received from the data transmission / reception unit 27, and sends the control signal via the data transmission / reception unit 27. Are transmitted to the terminal, and the output level state of the terminal is stored in the information data memory 28.
[0028]
The arithmetic circuit 30 controls the terminal output level so that Lmu ≧ Lt ≧ Lml and the terminal output level are between both reference values, assuming that the terminal output level Lt, the reference upper limit value Lmu, and the reference lower limit value Lml. When the level is below the reference lower limit value, an output up signal is sent. When the terminal output level exceeds the reference upper limit value, an output down signal is sent and adjusted, and the terminal output level does not exceed the reference lower limit value. Is configured to transmit an unadjustable signal or an output level lowering signal.
[0029]
Next, an outline of the output level adjustment procedure of the terminal used in this embodiment will be described with reference to FIG.
When the power switch 10 (FIG. 1) of the communication terminal A is closed, a location registration request is transmitted (50), and the base station 20 receives the location registration request signal (51).
The terminal output level is measured by the terminal output level calculation circuit 30 of the base station 20, and when the output level is not within the predetermined range, a control signal is transmitted (52).
The terminal that has received the control signal performs output level adjustment (53) in the output level adjustment circuit 18, and transmits a location registration request signal.
After the exchange of the control signal and the location registration request signal within a predetermined time, if the terminal output level still does not rise within the reference value, the terminal output level calculation circuit 30 of the base station determines that adjustment is impossible, A terminal output adjustment impossible notification is transmitted (54).
The terminal that has received the notification of incapability displays a mark in the form of a battery on the display unit and flashes and flashes the mark (55).
[0030]
When a call signal is transmitted from the terminal (56) and the base station 20 receives the call signal of the terminal (57), if the terminal output level cannot be adjusted by the location registration request signal, a terminal output level adjustment impossible notification is sent. A call is made and a call response (58) is made.
The terminal receives the terminal output level non-adjustable signal, displays a battery mark on the display unit 4 together with an output level non-adjustable warning by voice, and flushes the mark (59).
[0031]
When this terminal is ignored and the terminal transmits the telephone number of the other party (60), the base station 20 receives the telephone number (61) and transmits a calling signal to the other terminal (62).
Receiving this call signal (63), terminal B rings a bell if the terminal owner is not nearby, but sends a busy signal (64) if it is busy.
[0032]
FIG. 6 is an explanatory diagram of the operation procedure of the voice mail (electronic mail) function. In the figure, when the busy signal from terminal B is transmitted 15 times (65), the base station confirms it (66) and notifies terminal A of acceptance of voice mail (67). At this time, if the output level of the terminal A cannot be adjusted, the warning is performed by sound and flushing of the display unit. For example, the voice tells "Your terminal's output is low and cannot be adjusted, but the other party does not, so you can accept voice mail."
[0033]
A voice mail message and a calling time are designated from the terminal (69). For example, after the function key 7d of the terminal 1 is pressed and a message is transmitted, the # key is used to perform a key input operation of (# 1413 #) as meaning of 1 pm on the 14th.
Upon receiving the message content and the calling time, the base station 20 stores and saves it in the memory 31 (70), and makes a call to the terminal B on the designated date and time (71).
[0034]
Upon receiving this call signal (72), terminal B transmits an off-hook signal (73), and when base station 20 receives the signal (74), it transmits a message (75) and terminal B receives the message. (76), an on-hook signal is transmitted (77), and when the base station 20 receives the on-hook signal (78), the base station 20 deletes the message content (79) and ends (80).
[0035]
FIG. 7 is a first half operation procedure explanatory diagram illustrating the operation of the call memo function. In the figure, when the terminal A transmits the destination telephone number (60), the terminal B transmits the off-hook signal (81), and the call is started (84), the call memo is stored in the memory 31 of the base station 20. Recording begins (85).
When the call is finished (86) and the call memo key 7c of the terminal 1 is pressed, a save signal for requesting saving as a call memo is sent (87).
Upon receiving this stored signal, the base station 20 assigns a storage number to the call memo, notifies the terminal of the storage number, and stores the call memo (89).
When the terminal receives the storage number, it stores it in the memory 12 (90).
If there is no storage request from the terminal A or B, it is deleted appropriately.
[0036]
FIG. 8 shows a call memo playback procedure which is an operation procedure in the latter half of the call memo function. In the figure, when the playback key 7e and the call key 5a are pressed while the call memo storage number is displayed on the display unit 4 of the terminal 1, the playback and storage numbers are transmitted together with the call (94). A memo playback request is made.
Receiving this reproduction request (95), the base station 20 searches the memory 31 by the storage number from the information data search circuit 29 and sends a call memo to the terminal (96).
[0037]
When the playback and listening of the call memo is finished (98), the terminal presses the call memo erase signal, for example, presses # 000 # and the call memo key 7c. If a state that does not require a memo is checked (101), the contents of the call memo are erased and the process ends (103).
Even when the call memo erasure signal is not received from the terminal, it is erased appropriately taking into consideration the storage capacity of the memory 31 as in the case where the above-described storage number request is received.
[0038]
Next, the flow of the present embodiment in the base station 20 will be described in detail with reference to FIGS.
9, when the power switch 10 (FIG. 2) of the terminal 1 is pressed, a terminal location registration request signal is transmitted. When the base station 20 receives the location registration request signal (151), the presence / absence of a call signal is determined. (102) If a call signal has been received and a reproduction key and a call memo storage number have been received (153), it is determined that a call memo reproduction request has been made, and the process proceeds to step C. If not, it is determined whether the terminal output level measurement is completed (154). If it is completed, the process proceeds to Step B.
[0039]
If the terminal call signal is not received (152) and the terminal output level measurement is not completed (154), the terminal output level measurement (155) is performed.
If the terminal output level is within the normal range, the process returns to the standby state (150). If the terminal output level is not within the normal level, an output level adjustment command (157) is issued and the incoming terminal location registration request signal When the terminal output level is not within the normal range, it is determined whether or not the output level adjustment is complete, for example, whether or not a predetermined time has elapsed (160). If there is, the loop of steps 157, 158, 159, 160 is further followed, and if the output level adjustment is completed and the output level adjustment is impossible (161), an output adjustment impossible notification is sent to the terminal (162) and waits. Return to state (150).
[0040]
Next, the flow of the base station when a terminal is called will be described. In FIG. 9, when the terminal output level measurement is completed (154), the process proceeds to Step B in FIG.
In FIG. 10, when the terminal output level cannot be adjusted, the above-described warning is sent to the terminal (164), and a warning instruction is given to the voice and the display unit.
When a call is made from the terminal and the destination telephone number is received (166), the base station 20 calls (167) the other terminal, and when receiving an off-hook signal (168), the contents of the call are recorded (169). .
When the call is finished and a storage signal is received from the terminal, the storage number is transmitted and the process returns to the standby state (150).
If neither the terminal A nor the stored signal is received from B, the process proceeds to step E in FIG.
[0041]
In FIG. 10, when the base station 20 makes a call to the partner (167) and no off-hook signal is received from the partner terminal (168), the process proceeds to step D (105).
In FIG. 11, when the busy signal is received 15 times (172), if the output level of the terminal A cannot be adjusted (173), the terminal A is warned (174) and a message acceptance signal is transmitted (106).
Message reception is started (176), a message is received from the terminal, and message recording is completed (177).
When a message is transmitted to the partner terminal at the designated time of the terminal (178) and message communication is completed (179), the message content is deleted (180) and the process ends (181).
[0042]
Next, the operation in the base station at the time of transmitting a call memo will be described using the flowchart of FIG.
In FIG. 9, when a call memo reproduction request and storage number are received together with the call signal of the terminal (153), the process proceeds to step C in FIG.
When the contents of the memo are transmitted (182) and the transmission of the memo is completed (183), it is determined whether a memo erasing signal is received from the terminal A (184). It is determined whether or not the terminal B has requested to save the call memo (185), and if it has been requested, it is determined whether or not a memo erasure signal has been received from the terminal B (186) and the memo erasure signal is received. Is received (189), the process ends (190).
[0043]
On the other hand, it is conceivable that both the terminal A and the terminal B are left as they are because they forget to send the erasure signal or intend to reproduce again later.
Therefore, in such a case, the contents of the call memo are automatically deleted when a predetermined time, for example, 24 hours elapses.
That is, as shown in FIG. 12, when a memo erasure signal is not received from terminal A (184), after a predetermined time has elapsed (187), and when a memo erasure signal is not received from terminal B (188), The contents of the memo are deleted (189).
[0044]
In the above embodiment, the busy signal of the other party is detected and the voice mail is accepted by the terminal. However, the present invention is not limited to this, and the terminal is operated by operating the voice message key 7d of the terminal. You may accept by request.
A plurality of delivery destinations may be designated.
In addition, a delivery confirmation key may be provided on the terminal, or a delivery confirmation may be transmitted to the transmission side after voice mail is sent to the other party by a function key operation or the like.
In addition, it is explained that the record of the call memo is to make all calls, save what was requested to be saved, and erase what is not requested, but at the time of the terminal call signal or at the start of incoming call, A recording operation may be performed by sending a call memo request signal.
[0045]
In this embodiment, the memory 31 in the radio base station is disclosed as the memory of the radio base station. However, the present invention is not limited to this, and an external memory wired to the radio base station may be used. Of course, the memory may be a wirelessly connected memory that is guaranteed not to cause radio wave interference.
[0046]
As described above, according to this embodiment, since the database for voice mail (alternate reception) is provided for each base station, the capacity of the database does not increase.
In addition, it is possible to prevent as much as possible the problem that the proxy reception data becomes unclear due to radio wave interference, a decrease in the transmission output of the terminal, and the like.
[0047]
In addition, since the call memo is recorded in the memory of the radio base station, the call memo can be stored in a memory having a larger capacity than that built in the terminal, and the entire call can be recorded.
In addition, the memory can be configured to be shared with a voice mail (e-mail) memory, and it is not necessary to provide a separate memory for a call memory. is there.
[0048]
In addition, when the call memo is configured to record all calls once and save them by a stored signal from the terminal , all calls are recorded for each call, There is no record omission when it becomes.
Further, when the call memo is configured to be recorded by a call memo recording request signal from the terminal, an unnecessary call memo is not recorded, and it is not necessary to prepare a large-capacity memory.
In addition, since the call memo is configured to be deleted after a call memo erasure request signal from the terminal or after a predetermined time, the call memo after the call memo is reproduced is not stored in a record state indefinitely, The memory can be effectively used to prevent an increase in capacity.
[0049]
【The invention's effect】
As described above, according to the present invention, since a database for voice mail (alternate reception) is provided for each base station, the database does not increase in capacity , and the proxy reception data becomes unclear. There is an effect that the problem can be prevented.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a mobile communication system used in an embodiment of the present invention.
FIG. 2 is a diagram illustrating an external configuration of a communication terminal used in an embodiment of the present invention.
FIG. 3 is a circuit block diagram of a communication terminal.
FIG. 4 is a circuit block diagram of a radio base station.
FIG. 5 is an explanatory diagram of an operation procedure of an output level adjustment function of the terminal.
FIG. 6 is an explanatory diagram of an operation procedure of a voice mail function.
FIG. 7 is an explanatory diagram of the first half of the operation procedure of the call memo function;
FIG. 8 is an explanatory diagram of the latter half of the operation procedure of the call memo function.
FIG. 9 is a flowchart at the time of terminal output level adjustment in the base station.
FIG. 10 is a flowchart when a terminal originates a call in a base station.
FIG. 11 is a flowchart at the time of voice mail in the base station.
FIG. 12 is a flowchart when a call memo is transmitted in the base station.
FIG. 13 is a conventional example showing an alternate reception system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Communication terminal 3 Earpiece 4 Display part 8 Transmission part 10 Power switch 11, 21 CPU
12, 31 Memory 13, 23 ROM
14, 24 Wireless communication circuit 17 Input / output device 18 Output level adjustment circuit 20 Wireless base station 25 Telephone line interface unit 26, 27 Data transmission / reception unit 28 Information data memory 29 Information data search circuit 30 Terminal output level calculation circuit 40 Data management center

Claims (6)

In a radio base station that relays a call from a portable communication terminal to a destination terminal,
A database for voice mail for storing transmission items from the portable communication terminal to the counterpart terminal;
Calling voice mail means for proxy transmission of the transmission items to the destination terminal;
Wherein when receiving a location registration request signal from the portable communication terminal, wherein when the transmission output level transmission output level by measuring the portable communication terminal is not in a predetermined range, and transmits a control signal to said mobile communication terminal Terminal output level adjusting means for instructing the portable communication terminal to adjust its transmission output level;
Have a memory means for storing the transmission output level when the transmitting the control signal,
Upon receipt of designation of voice mail transmission items and calling time from the portable communication terminal to the destination terminal, the voice mail database stores and stores the designated date and time by the calling voice mail means. A radio base station that calls a communication item to a partner terminal . The voice mail database is shared with a database for call memos that stores call contents between portable communication terminals ,
When a call between the portable communication terminal and the partner terminal is started, recording of the call content starts in the database, and after the call ends, when a signal requesting storage of the call content is received from the portable communication terminal, The radio base station according to claim 1 , wherein a storage number is assigned to the contents of the call and stored, and the storage number is notified to the portable communication terminal .   An output level adjustment impossible notification means for transmitting an output level adjustment impossible notification to the portable communication terminal if the transmission output level of the portable communication terminal is not improved after transmitting the control signal. Item 3. The radio base station according to Item 1 or 2.   An erasure unit for erasing the transmission matter after a predetermined time elapses after receiving the erasure signal instructing erasure of the transmission matter from the portable communication terminal after transmitting the transmission matter to the counterpart terminal. The radio base station according to claim 1, further comprising: Output level adjustment means for adjusting a transmission output level when used with the radio base station according to claim 3 and receiving the control signal;
Warning means for giving a warning when receiving the notification that the output level cannot be adjusted;
A portable communication terminal comprising key means for requesting use of the voice mail database.   A mobile communication system comprising a plurality of radio base stations according to claim 3 and a plurality of portable communication terminals according to claim 5.

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