JP4038091B2

JP4038091B2 - Communication terminal, communication system including the same, and call control failure countermeasure method

Info

Publication number: JP4038091B2
Application number: JP2002226306A
Authority: JP
Inventors: 隆弘佐々木; 廣行佐藤
Original assignee: Hitachi Communication Technologies Ltd
Current assignee: Hitachi Communication Technologies Ltd
Priority date: 2002-08-02
Filing date: 2002-08-02
Publication date: 2008-01-23
Anticipated expiration: 2022-08-02
Also published as: JP2004072256A

Description

【０００１】
【発明の属する技術分野】
本発明は、他の通信端末とＩＰパケット通信を行うために、複数の呼制御装置のうちの一つに呼制御される通信端末、これを含む通信システム、及び呼制御障害の対策方法に関する。
【０００２】
【従来の技術】
従来、ＩＰパケット通信システムとしては、例えば、図８に示すようなものがある。
【０００３】
このＩＰパケット通信システムは、ＩＰパケット通信を行う複数の通信端末７，８と、複数の通信端末７，８相互間の呼制御を行う呼制御装置３と、を有している。複数の通信端末７，８や呼制御装置３の相互間は、ＬＡＮ回線９で接続されている。通信端末７，８としては、ＩＰ電話機や、ＩＰゲートウエイや、一般電話機が複数接続されるＩＰ・ＰＢＸ（Private Branch Exchanger）等があげられる。
【０００４】
呼制御装置３は、無停止呼サービスを行うために、第１の呼制御部５ａと、第２の呼制御部５ｂと、これらの呼制御部５ａ，５ｂを管理する呼制御管理部６と、ＩＰパケット通信を行うための通信インタフェース４と、を有している。この呼制御装置３は、仮に、第１の呼制御部５ａが運用状態である際には、第２の呼制御部５ｂは待機状態になっている。この際、呼制御管理部６は、運用状態にある第１の呼制御部５ａに障害が発生していないかを常時監視していると共に、第１の呼制御部５ｂが所有している呼サービス設定情報や呼制御状態情報をそのまま第２の呼制御部５ｂに与えている。言い換えると、第１の呼制御部５ａが呼サービス情報や呼制御状態情報を取得すると、これとほぼ同時にこれらの情報を第２の呼制御部５ｂにデッドコピーしている。なお、呼サービス設定情報とは、各端末が設定し得る呼サービスに関する情報で、例えば、端末自身への着信を他の端末へ転送する着信転送サービス等の各種サービスである。また、呼制御状態情報とは、いずれの端末が通話中であるか等、各端末の状態に関する情報である。
【０００５】
この呼制御装置３は、第１の呼制御部５ａに障害が生じた場合、呼制御管理部６が、この障害を直ちに検知して、第１の呼制御部５ａの全ての情報を所有している待機中の第２の呼制御部５ｂを起動させて、無停止呼サービスを実現している。
【０００６】
【発明が解決しようとする課題】
しかしながら、以上の従来技術では、第１の呼制御部５ａの他に、予備機としての第２の呼制御部５ｂを設けておくと共に、二つの呼制御部５ａ，５ｂから独立したハードウェアーとしての呼制御管理部６を設けておく必要があるため、装置コストがかさむという問題点がある。特に、呼制御管理部６は、前述したように、第１の呼制御部５ａが端末の呼サービス設定情報や呼制御状態情報を取得すると、ほぼ同時に、これらの情報を第２の呼制御部５ｂにデッドコピーするために、特殊なハードウェアーで構成され、非常に高価である。
【０００７】
本発明は、このような従来技術の問題点に着目してなされたもので、装置コストを抑えつつ、呼制御に障害が生じても対応することができる、装置、これを含む通信システム、及び呼制御障害の対策方法を提供することを目的とする。
【０００８】
【課題を解決するための手段】
前記目的を達成するための通信端末は、
他の通信端末とＩＰパケット通信を行うために、複数の呼制御装置のうちの一つに呼制御される通信端末であって、
前記他の通信端末及び複数の前記呼制御装置との間でＩＰパケット通信を行う通信手段と、
複数の前記呼制御装置のうちの一の呼制御装置が呼制御可能な運用状態で、他の呼制御装置が待機状態であるときに、前記通信手段を介して、該一の呼制御装置から呼制御可能な運用状態である旨を一定時間毎に受信して、該運用状態の該一の呼制御装置を監視し、該呼制御可能な運用状態である旨を該一定時間以上受信できない場合には、該一の呼制御装置による呼制御に障害が発生していると認識して、該一の呼制御装置に対する呼制御接続を該通信手段に解放させる監視手段と、
を備えていることを特徴とするものである。
【０００９】
ここで、前記通信端末の前記監視手段は、前記呼制御可能な運用状態である旨を前記一定時間以上受信できず、前記一の呼制御装置に対する呼制御接続を解放させた後、複数の前記呼制御装置のうち、現時点で該呼制御可能な運用状態である呼制御装置からの応答を、前記通信手段を介して、要求することが好ましい。
【００１７】
ここで、前記目的を達成するための通信システムは、
第一の呼制御装置と、
第二の呼制御装置と、
請求項１に記載の複数の通信端末と、
を備え、
前記第１の呼制御装置と前記第２の呼制御装置と複数の前記通信端末のそれぞれとは、互いに回線で接続され、
前記第一の呼制御装置は、
複数の前記通信端末及び前記第二の呼制御装置との間でＩＰパケット通信を行う通信手段と、複数の該通信端末の呼制御を行う呼制御手段と、該呼制御手段による呼制御に障害が発生しているか否かを監視し、障害が発生しておらず呼制御可能状態である際に該第二の呼制御装置へ動作可通知を送り、該呼制御手段による呼制御に障害が発生していることを認識すると、該第二の呼制御装置への前記動作可通知の送信を中止して、該呼制御手段を運用状態から待機状態にする監視手段と、を有し、
前記第二の呼制御装置は、
複数の前記通信端末及び前記第一の呼制御装置との間でＩＰパケット通信を行う通信手段と、複数の該通信端末の呼制御を行う呼制御手段と、該通信手段を介して、該第一の呼制御装置から呼制御可能状態であることを示す動作可通知を受け付け、該動作可通知が一定時間以上受信できない場合、該第一の呼制御装置が呼制御不可状態であると判断し、待機状態の前記呼制御手段を起動させて、運用状態にする監視手段と、を有し、
複数の通信端末のうち、一の通信端末と他の通信端末との間で通信する際には、前記第１の呼制御装置の前記呼制御手段と前記第２の呼制御装置の呼制御手段とのうち、前記運用状態の呼制御手段により、呼制御が行われる、
ことを特徴とするものである。
【００１８】
前記目的を達成するための他の通信システムは、
第１の呼制御装置と、
前記第１の呼制御装置に対して、ＬＡＮ（ Local Area network ）回線を介して接続されている複数の、請求項１に記載の通信端末（以下、第１の通信端末とする）と、
前記第１の呼制御装置に対して、ＷＡＮ（ Wide Area network ）を介して接続されている第２の呼制御装置と、
前記第２の呼制御装置に対して、ＬＡＮ（ Local Area network ）回線を介して接続されている複数の、請求項１に記載の通信端末（以下、第２の通信端末とする）と、
を備え、
前記第一の呼制御装置は、
複数の前記通信端末及び前記第二の呼制御装置との間でＩＰパケット通信を行う通信手段と、複数の該通信端末の呼制御を行う呼制御手段と、該呼制御手段による呼制御に障害が発生しているか否かを監視し、障害が発生しておらず呼制御可能状態である際に該第二の呼制御装置へ動作可通知を送り、該呼制御手段による呼制御に障害が発生していることを認識すると、該第二の呼制御装置への前記動作可通知の送信を中止して、該呼制御手段を運用状態から待機状態にする監視手段と、を有し、
前記第二の呼制御装置は、
複数の前記通信端末及び前記第一の呼制御装置との間でＩＰパケット通信を行う通信手段と、複数の該通信端末の呼制御を行う呼制御手段と、該通信手段を介して、該第一の呼制御装置から呼制御可能状態であることを示す動作可通知を受け付け、該動作可通知が一定時間以上受信できない場合、該第一の呼制御装置が呼制御不可状態であると判断し、待機状態の前記呼制御手段を起動させて、運用状態にする監視手段と、を有し、
複数の前記第１の通信端末と複数の前記第２の通信端末とのうちのいずれか二つの通信端末相互間で通信する際には、前記第１の呼制御装置の前記呼制御手段と前記第２の呼制御装置の呼制御手段とのうち、前記運用状態の呼制御手段により、呼制御が行われる、
ことを特徴とするものである。
【００１９】
また、前記目的を達成するための呼制御障害の対策方法は、
複数の通信端末とＩＰパケット通信が可能な第１の呼制御装置及び第二の呼制御装置を設け、
前記第１の呼制御装置は、
複数の前記通信端末の呼制御を行う呼制御工程と、
前記呼制御工程での呼制御に障害が発生しているか否かを監視し、障害が発生しておらず呼制御可能状態である際に前記第２の呼制御装置へ一定時間毎に動作可通知を送り、前記呼制御工程での呼制御に障害が発生していることを認識すると、該第２の呼制御装置への前記動作可通知の送信を中止して、前記呼制御工程を運用状態から待機状態にする監視工程と、
を実行し、
前記第２の呼制御装置は、
複数の前記通信端末の呼制御を行う呼制御工程と、
前記第１の呼制御装置から呼制御可能状態であることを示す動作可通知を受け付け、該動作可通知が前記一定時間以上受信できない場合、該第１の呼制御装置が呼制御不可状態であると判断し、待機状態の前記呼制御工程を起動させて、運用状態にする監視工程と、
を実行し、
前記第１の呼制御装置と前記第２の呼制御装置とのうち、前記呼制御工程が運用状態である呼制御装置の前記監視工程では、複数の前記通信端末に対して、呼制御可能な状態である旨を一定時間毎に通知し、
複数の前記通信端末は、前記呼制御可能な運用状態である旨を前記一定時間以上受信できないときには、前記第１の呼制御装置と前記第２の呼制御装置とのうち、現時点で該呼制御可能な運用状態である呼制御装置からの応答を要求し、
前記第１の呼制御装置と前記第２の呼制御装置とのうち、現時点で該呼制御可能な運用状態である呼制御装置の監視工程では、複数の前記通信端末からの前記応答要求に対して、該応答要求を送信してきた前記通信端末に対して、該呼制御装置のＩＰアドレスを送信する、
ことを特徴とするものである。
【００２１】
【発明の実施の形態】
以下、本発明に係るＩＰパケット通信システムの各種実施形態について、図面を用いて説明する。
【００２２】
まず、図１〜図４を用いて、本発明に係る第１の実施形態としてのＩＰパケット通信システムについて説明する。
【００２３】
本実施形態のＩＰパケット通信システムは、図１に示すように、ＩＰパケット通信を行う複数の通信端末２０，２８，２９と、複数の通信端末相互間の呼制御を行う第１及び第２の呼制御装置１０ａ，１０ｂと、を有している。複数の通信端末２０，２８，２９や各呼制御装置１０ａ，１０ｂの相互間は、ＬＡＮ回線９で接続されている。この実施形態において、複数の通信端末２０，２８，２９のうち、一つはＩＰゲートウエイ２０で、残りはＩＰ電話機２８，２９である。
【００２４】
第１及び第２の呼制御装置１０ａ，１０ｂは、いずれも、ＩＰパケット通信を行うための通信インタフェース１１ａ，１１ｂと、各通信端末相互間の呼制御を実際に行う呼制御部１２ａ，１２ｂと、この呼制御部１２ａ，１２ｂ及び他方の呼制御装置１０ｂ，１０ａの状態を監視する監視部１３ａと、各端末２０，２８，２９の呼制御サービスに関する設定情報を管理する設定情報管理部１４ａと、呼サービス設定情報や各通信端末のＩＰアドレス等を記憶する記憶部１５ａ，１５ｂと、を備えている。
【００２５】
監視部１３ａ，１３ｂは、呼制御部１２ａ，１２ｂ及び通信インタフェース１１ａ，１１ｂを監視し、これらの障害がなければ、通信インタフェース１１ａ，１１ｂを介して、呼制御可能状態であることを示す動作可能通知を他方の呼制御装置に送信する。また、他方の呼制御装置からは、通信インタフェース１１ａ，１１ｂを介して、動作可能通知を受信する。監視部１３ａ，１３ｂは、呼制御部１２ａ，１２ｂ及び通信インタフェース１１ａ，１１ｂの監視結果、及び他方の呼制御装置からの動作可能通知に基づき、呼制御部１２ａ，１２ｂ及び設定情報管理部１４ａ，１４ｂを待機状態から運用状態へ、又は運用状態から待機状態へ切り替える。
【００２６】
設定情報管理部１４ａ，１４ｂは、運用状態の際、通信インタフェース１１ａ，１１ｂを介して、記憶部１５ａ，１５ｂに記憶されている呼サービス設定情報を他方の呼制御装置へ送信し、待機状態の際には、他方の呼制御装置から呼サービス設定情報を取得し、記憶部１５ａ，１５ｂに登録する。
【００２７】
各通信端末２０，２８，２９は、ＩＰパケット通信を行うための通信インタフェース２１と、この通信インタフェース２１で受信したＩＰパケットを音声信号等に変換する一方で、音声信号等をＩＰパケットに変換する符号化・復号化部２２と、符号化・復号化部２２で復号化された音声信号をアナログ信号に変換するＡ／Ｄ変換器２３と、二つの呼制御装置１０ａ，１０ｂの状態を監視する監視部２５と、を有している。なお、通信端末がＩＰゲートウエイ２０である場合には、Ａ／Ｄ変換器２３に、ＰＢＸ等との間で音声信号等を送受信するためのインタフェース２４が接続されることになる。また、通信端末がＩＰ電話機２８，２９である場合には、Ａ／Ｄ変換器に、ハンドセット等が接続されることになる。
【００２８】
次に、以上で説明した本実施形態の通信システムの動作について、図２を用いて説明する。なお、同図では、初期設定により、第１の呼制御装置１０ａの呼制御部１１ａが運用状態で、この第１の呼制御装置１０ａが運用系として働き、第２の呼制御装置１０ｂの呼制御部１１ｂが待機状態で、この第２の呼制御装置１０ｂが予備系として働くよう、設定されているものとする。また、通信端末２０は、運用系として働いている第１の呼制御装置１０ａに対して接続運用中であるとする。
【００２９】
運用系である第１の呼制御装置１０ａの監視部１３ａは、定期的に、自身の呼制御部１２ａ及び通信インタフェース１１ａを監視し、呼制御可能な状態であることを確かめて、通信インタフェース１１ａ及びＬＡＮ回線９を介して、動作可通知を第２の呼制御装置１０ｂへ送信する（ステップ１）。また、予備系である第２の呼制御装置１０ｂの監視部１３ｂも、以上と同様に、動作可通知を定期的に第１の呼制御装置１０ａへ送信する（ステップ２）。また、第１の呼制御装置１０ａの設定情報管理部１４ａは、定期的に、記憶部１５ａに記憶されている各通信端末の呼サービス設定情報を、通信インタフェース１１ａ及びＬＡＮ回線９を介して、第２の呼制御装置１０ｂへ送信する（ステップ３）。なお、各通信端末２０の呼サービス設定情報は、各通信端末２０において、ユーザ等による操作で設定され、この情報が、後述の呼制御通信（ステップ４）で、呼制御装置１０ａの設定情報管理部１４ａに渡される。
【００３０】
通信端末２０が他の通信端末と通話する場合には、この通信端末２０が運用系であると認識している呼制御装置１０ａとの間で呼制御通信が行われる、つまり、この通信端末２０と他の通信端末との間の呼制御が呼制御装置１０ａに依頼される(ステップ４）。この呼制御通信により、他の通信端末との通信回線が確立すると、他の通信端末との間で通話が可能になる。
【００３１】
運用系呼制御装置１０ａの監視部１３ａは、動作可通知を送信する際と同様、定期的に、自身の呼制御部１２ａ及び通信インタフェース１１ａの監視し、呼制御可能な状態であることを確かめて、通信インタフェース１１ａ及びＬＡＮ回線９を介して、呼制御可能な状態であることを示すと共に、その応答を要求する動作確認要求を各通信端末２０に送信する（ステップ５）。通信端末２０の監視部２５は、この動作確認要求を受け取ると、この動作確認要求元が運用系であると認識する。そして、この動作確認要求に対する返答として、動作確認応答を運用系呼制御装置１０ａへ送信する（ステップ６）
つまり、運用系呼制御装置１０ａは、定期的に、例えば、５秒毎に、動作可通知及び呼サービス設定情報を予備系呼制御装置１０ｂへ送信し（ステップ１，３）、予備系呼制御装置１０ｂは、定期的に、動作可通知を運用系呼制御装置１０ａへ送信する（ステップ２）。さらに、運用系呼制御装置１０ａは、定期的に、各通信端末２０に動作確認要求を送信する（ステップ５）。
【００３２】
以上のように、二つの呼制御装置１０ａ，１０ｂが互いに他方の呼制御装置１０ｂ，１０ａに対して動作可通知を送信し合うことで、他方の呼制御装置が呼制御可能な状態であるか否かを認識することができる。また、運用系呼制御装置１０ａが定期的に呼サービス設定情報を予備系呼制御装置２０ｂへ送信することで、この呼サービス設定情報の共有化を図ることができる。また、運用系呼制御装置１０ａが定期的に動作確認要求を送信することで、各端末１０はいずれの呼制御装置が現在運用系であるかを認識することができる。
【００３３】
運用系呼制御装置１０ａの呼制御部１２ａ又は通信インタフェース１１ａに障害が生じると（ステップ７）、運用系呼制御装置１０ａの監視部１３ａは、この障害を認識し、現在の予備系呼制御装置１０ｂへの動作可通知及び各通信端末への動作確認要求を停止し、呼制御部を待機状態にして、予備系に切り替える（ステップ８）。
【００３４】
予備系である第２の呼制御装置１０ｂの監視部１３ｂは、当初、運用系であった第１の呼制御装置１０ａから、一定期間、動作可通知が送信されてこないことから、この第１の呼制御装置１０ａに障害が発生したと認識して、待機状態であった呼制御部１２ｂを運用状態にして、当該第２の呼制御装置１０ｂを運用系に切り替える（ステップ９）。
【００３５】
また、各通信端末２０の監視部２５も、当初、運用系であった第１の呼制御装置１０ａから、一定期間、動作確認要求が送信されてこないことから、この第１の呼制御装置１０ａに障害が発生したと認識して、この第１の呼制御装置１０ａとの接続を解放する（ステップ１０）。
【００３６】
各通信端末２０の監視部２５は、呼制御可能な呼制御装置を検索するため、端末自身のＩＰアドレスと共に、検索応答要求をマルチキャストで送信する（ステップ１１）。この検索応答要求に対して、予備系に切り替わった第１の呼制御装置１０ｂは応答せず、運用系に切り替わった第２の呼制御装置１０ｂの監視部１３ｂは、検索応答要求のあった通信端末２０に対して、検索応答と共に第２の呼制御装置１０ｂのＩＰアドレスを送信して、現在運用状態にある呼制御装置１０ｂを認識させると共に（ステップ１２）、検索応答要求のあった通信端末２０のＩＰアドレスを記憶する（ステップ１５）。検索応答と共に第２の呼制御装置１０ｂのＩＰアドレスを受信した通信端末２０の通信インタフェース２１は、このＩＰアドレスを記憶し（ステップ１３）、その後、この運用系になった第２の呼制御装置１０ｂとの間で、呼制御通信のための接続処理を行う（ステップ１４）。
【００３７】
運用系に切り替わった第２の呼制御装置１０ｂの監視部１３ｂは、第１の呼制御装置１０ａが運用系であったときと同様に、定期的に、自身の呼制御部１２ｂ及び通信インタフェース１１ｂを監視し、呼制御可能な状態であることを確かめて、動作可通知を予備系である第１の呼制御装置１０ａへ送信すると共に（ステップ２１）、各通信端末に動作確認要求を送信する（ステップ２５）。この動作確認要求に対して、各通信端末２０は、現在運用系である第２の呼制御装置１０ｂに動作確認応答を返す（ステップ２６）。また、第２の呼制御装置１０ｂの設定情報管理部１４ｂは、呼サービス設定情報を第１の呼制御装置１０ａへ送信する（ステップ２３）。予備系である第１の呼制御装置１０ａの監視部１３ａは、自身の呼制御部１２ａ及び通信インタフェース１１ａを監視し、故障等の障害が復旧して呼制御可能な状態になると、第２の呼制御装置１０ｂに対して、動作可通知を定期的に送信し始める。
【００３８】
通信端末２０が他の通信端末と通話する場合には、ステップ４と同様に、この通信端末２０の監視部が運用系であると認識している呼制御装置、この場合は、第２の呼制御装置１０ｂとの間で呼制御通信が行われる（ステップ２４）。この呼制御通信により、他の通信端末との通信回線が確立すると、他の通信端末との間で通話が可能になる。
【００３９】
なお、以上で説明したステップ１１〜１４の処理は、各通信端末２０の立ち上げ時にも、各通信端末２０が運用系呼制御装置を認識等するために、初期処理として行われる。具体的は、図３のフローチャートに示すように、まず、通信端末２０の監視部２５が、呼制御可能な呼制御装置を検索するため、端末自身のＩＰアドレスと共に、検索応答要求をマルチキャストで送信する（ステップ１１）。続いて、監視部２５は、この検索応答要求に対する運用系呼制御装置からの検索応答の受信を待ち（ステップ１２）、この検索応答を受信すると、監視部２５は、検索応答と共に送られてきた運用系呼制御装置のＩＰアドレスを記憶部２６に登録する（ステップ１３）。さらに、監視部２５は、通信インタフェース２１に、運用系呼制御装置との間での呼制御通信を行うための接続処理を実行させる（ステップ１４）。
【００４０】
その後、この通信端末２０が他の通信端末と通話する場合には、この通信端末２０の記憶部２６に運用系として記憶されている呼制御装置との間で、呼制御通信が行われる（ステップ２４）。また、監視部２５は、運用系呼制御装置からの動作確認要求を定期的に受信しているか否かを判断し（ステップ２５）、動作確認要求を受信できない場合には、ステップ１１に戻り、動作確認要求を受信できた場合には、運用系呼制御装置へ動作確認応答を送る（ステップ２６）。
【００４１】
ここで、図４を用いて、各呼制御装置の動作について、まとめて説明する。
【００４２】
運用系呼制御装置は、障害がない場合、予備系呼制御装置に障害が在ろうが無かろうが、予備系呼制御装置に対して、動作可通知及び呼サービス設定情報を定期的に送信する。また、通信端末に対しては、動作確認要求を送信し、検索応答要求に対して検索応答を返し、呼制御接続時の呼サービス指示を与える。
【００４３】
運用系呼制御装置に障害が発生し、この運用系が予備系に移行し、予備系が運用系に移動した場合、予備系から運用系に移動した呼制御装置は、運用系から予備系に移行した呼制御装置に対して、この呼制御装置に障害が在ろうが無かろうが、動作可通知及び呼サービス設定情報を定期的に送信する。また、通信端末に対しては、動作確認要求を送信し、検索応答要求に対して検索応答を返し、呼制御接続時の呼サービス指示を与える。
【００４４】
予備系呼制御装置は、障害がない場合、運用系呼制御装置に対して、動作可通知を定期的に送信する。運用系呼制御装置に対する呼サービス設定情報の送信、通信端末に対する動作確認要求の送信、通信端末からの検索応答要求に対する検索応答、呼制御接続時の呼サービス指示は、いずれも、運用系呼制御装置が行い、予備系呼制御装置は行わない。
【００４５】
運用系呼制御装置に障害が発生し、この運用系が予備系に移行した場合、運用系から予備系に移行した呼制御装置は、運用系呼制御装置に対する動作可通知及び呼サービス設定情報の送信を行わない。さらに、通信端末に対する動作確認要求の送信、通信端末からの検索応答要求に対する検索応答、呼制御接続時の呼サービス指示も行わない。
【００４６】
以上のように、本実施形態では、２台の呼制御装置１０ａ，１０ｂのうち、運用系呼制御装置１０ａに障害が生じても、予備系呼制御装置１０ｂが運用系となって、各通信端末相互の呼制御を行うので、呼制御障害による被害を最小限に抑えることができる。また、２台の呼制御装置１０ａ，１０ｂ相互間で、呼制御可能な状態であるか否かを通信で確認しあっているので、２台の呼制御装置１０ａ，１０ｂの他に別途、これらを管理する呼制御管理装置が不要になり、装置コストを抑えることができる。
【００４７】
次に、図５〜図７を用いて、本発明に係る第２の実施形態としてのＩＰパケット通信システムについて説明する。
【００４８】
本実施形態のＩＰパケット通信システムは、図５に示すように、ＩＰ網であるＷＡＮ（Wide Area network）１及びルータ等の中継装置２ａ，２ｂを介して、二つの通信拠点Ａ，Ｂが接続されているものである。各通信拠点Ａ，Ｂには、呼制御装置１０ａ，１０ｂと、前述の中継装置２ａ，２ｂと、複数の通信端末２０ａ，２９ａ，２０ｂ，２９ｂとを備えている。呼制御装置１０ａ，１０ｂ、中継装置２ａ，２ｂ、複数の端末２０ａ，２９ａ，２０ｂ，２９ｂ相互は、ＬＡＮ回線９ａ，９ｂで接続されている。つまり、第１の実施形態は、ある拠点内に２台の呼制御装置と複数の通信端末とを設けたものであるが、本実施形態は、ＷＡＮ１を介して、二つの通信拠点にそれぞれ一台ずつの呼制御装置と複数の通信端末とを設けたものである。
【００４９】
各拠点Ａ，Ｂの呼制御装置１０ａ，１０ｂは、第１の実施形態と同様に、ＩＰパケット通信を行うための通信インタフェース１１ａ，１１ｂと、各通信端末相互間の呼制御を実際に行う呼制御部１２ａ，１２ｂと、この呼制御部１２ａ，１２ｂ及び他方の呼制御装置の状態を監視する監視部１３ａ，１３ｂと、各端末の呼制御サービスに関する設定情報を管理する設定情報管理部１４ａ，１４ｂと、呼サービス設定情報等を記憶する記憶部１５ａ，１５ｂと、を備えている。
【００５０】
また、各拠点Ａ，Ｂの通信端末２０ａ，２０ｂも、第１の実施形態と同様に、ＩＰパケット通信を行うための通信インタフェース２１と、この通信インタフェース２１で受信したＩＰパケットを音声信号等に変換する一方で、音声信号等をＩＰパケットに変換する符号化・復号化部２２と、符号化・復号化部２２で復号化された音声信号をアナログ信号に変換するＡ／Ｄ変換器２３と、二つの呼制御装置の状態を監視する監視部２５と、記憶部２６と、を備えている。
【００５１】
次に、以上で説明した本実施形態の通信システムの動作について、図６を用いて説明する。なお、同図では、初期設定により、拠点Ａの第１の呼制御装置１０ａが運用系として働き、拠点Ｂの第２の呼制御装置１０ｂが予備系として働くよう、設定されているものとする。また、各拠点Ａ，Ｂの通信端末２０ａ，２０ｂは、運用系として働いている第１の呼制御装置１０ａに対して接続運用中であるとする。
【００５２】
運用系である第１の呼制御装置１０ａの監視部１３ａは、第１の実施形態と同様に、通信インタフェース１１ａ、中継装置２ａ，２ｂ及びＷＡＮ１を介して、動作可通知及び各通信端末の呼サービス設定情報を予備系である第２の呼制御装置１０ｂへ送信する（ステップ３１，３３）。また、予備系である第２の呼制御装置１０ｂの監視部１３ｂも、以上と同様に、動作可通知を定期的に第１の呼制御装置１０ａへ送信する（ステップ３２）。
【００５３】
拠点Ａ，Ｂの通信端末２０ａ，２０ｂが他の通信端末２０ｂ，２０ａと通話する場合には、この通信端末２０ａ，２０ｂが運用系であると認識している呼制御装置１０ａとの間で呼制御通信が行われる（ステップ３４ａ，３４ｂ）。
【００５４】
拠点Ａの運用系呼制御装置１０ａの監視部１３ａは、動作確認要求を各拠点Ａ，Ｂの通信端末２０ａ，２０ｂに送信する（ステップ３５ａ，３５ｂ）。各拠点Ａ，Ｂの通信端末２０ａ，２０ｂの監視部１３ａ，１３ｂは、この動作確認要求を受け取ると、この動作確認要求元が運用系であると認識し、この動作確認要求に対する返答として、動作確認応答を運用系呼制御装置１０ａへ送信する（ステップ３６ａ，３６ｂ）。
【００５５】
つまり、以上のステップ３１〜３６ｂまでの処理は、第１の実施形態におけるステップ１〜６までの処理と同様の処理である。
【００５６】
拠点Ａ，Ｂ間の中継回線に障害が生じた場合（ステップ３７）、運用系呼制御装置１０ａの監視部１３ａは、自身の呼制御部１２ａの障害ではないため、この中継回線障害を認識せず、拠点Ｂの予備系呼制御装置１０ｂへ動作可通知を送信する共に（ステップ３８）、拠点Ａ，Ｂの各通信端末２０ａ，２０ｂへ動作確認要求を送信する（ステップ４０ａ，４０ｂ）。また、拠点Ｂの予備系呼制御装置１０ｂの監視部１３ｂも、拠点Ａの運用系呼制御装置１０ａへ動作確認要求を送信する（ステップ３９）。しかしながら、拠点Ａ，Ｂ間の中継回線に障害が生じているため、拠点Ａの運用系呼制御装置１０ａから拠点Ｂへの動作可通知及び動作確認要求は、拠点Ｂに到達せず（ステップ３８，ステップ４０ｂ）、また、拠点Ｂの予備系呼制御装置１０ｂから拠点Ａへの動作可通知も、拠点Ａに到達しない（ステップ３９）。
【００５７】
拠点Ａの運用系呼制御装置１０ａは、拠点Ｂの予備系呼制御装置からの動作可通知を受信できないため、拠点Ｂで障害が生じたと認識して、以降、拠点Ａの通信端末２０ａにのみ、動作確認要求を送信し（ステップ４０ａ）、この端末２０ａから動作確認応答を受信する（ステップ４１ａ）。さらに、拠点Ａの通信端末とのみ、呼制御通信を行う（ステップ４２ａ）。但し、拠点Ｂへの動作確認要求の送信は、以降も定期的に行う（ステップ３８，３８，…）。
【００５８】
一方、拠点Ｂの予備系呼制御装置１０ｂの監視部１３ｂは、拠点Ａの運用系呼制御装置１０ａから、一定期間、動作可通知が送信されてこないことから（ステップ３８）、拠点Ａの運用系呼制御装置１０ａに障害が発生したと認識して、待機状態であった呼制御部１２ｂを運用状態にして、予備系であった第２の呼制御装置１０ｂを運用系に切り替える（ステップ４３）。
【００５９】
また、拠点Ｂの各通信端末２０ｂの監視部２５も、当初、運用系であった第１の呼制御装置２０ａから、一定期間、動作確認要求が送信されてこないことから（ステップ４０ｂ）、拠点Ａの第１の呼制御装置１０ａに障害が発生したと認識して、この第１の呼制御装置１０ａとの接続を解放する（ステップ４１）。
【００６０】
そして、拠点Ｂの各通信端末２０ｂの監視部２５は、呼制御可能な呼制御装置を検索するため、端末自身のＩＰアドレスと共に、検索応答要求をマルチキャストで送信する（ステップ４４）。この検索応答要求に対して、運用系に切り替わった第２の呼制御装置１０ｂの監視部１３ｂは、検索応答要求のあった拠点Ｂの通信端末２０ｂに対して、検索応答と共に第２の呼制御装置１０ｂのＩＰアドレスを送信して、現在運用状態にある呼制御装置１０ｂを認識させると共に（ステップ４５）、検索応答要求のあった通信端末２０ｂのＩＰアドレスを記憶する（ステップ４８）。検索応答と共に第２の呼制御装置１０ｂのＩＰアドレスを受信した通信端末２０ｂの通信インタフェース２１は、このＩＰアドレスを記憶部２５に記憶し（ステップ４６）、その後、この運用系になった第２の呼制御装置１０ｂとの間で、呼制御通信のための接続処理を行う（ステップ４７）。
【００６１】
運用系に切り替わった第２の呼制御装置１０ｂの監視部１３ｂは、第１の呼制御装置１０ａが運用系であったときと同様に、定期的に、自身の呼制御部１２ｂ及び通信インタフェース１１ｂを監視し、呼制御可能な状態であることを確かめて、動作可通知を拠点Ａの第１の呼制御装置１０ａへ送信すると共に（ステップ５２）、拠点Ｂの各通信端末２０ｂに動作確認要求を送信する（ステップ５０ｂ）。この動作確認要求に対して、拠点Ｂの各通信端末２０ｂは、動作確認応答を返す（ステップ５１ｂ）。
【００６２】
以上のように、中継回線に障害が発生した場合には、拠点Ａの第１の呼制御装置１０ａは、運用系を維持するものの、拠点Ａの各通信端末２０ａに対してのみ呼制御装置として機能し、当初、予備系であった拠点Ｂの第２の呼制御装置１０ｂは、運用系に切り替わるものの、拠点Ｂの各通信端末２０ｂに対してのみ呼制御装置として機能する。つまり、中継回線に障害が発生している際中は、各拠点の呼制御装置が、それぞれの拠点の運用系呼制御装置となる。
【００６３】
次に、図７を用いて、中継回線の障害が復旧した場合の動作について、説明する。
【００６４】
中継回線の障害が復旧すると(ステップ５５)、拠点Ｂの第２の呼制御装置１０ｂからの動作可通知が拠点Ａの第１の呼制御装置１０ａへ到達するようになる（ステップ５６）。同様に、拠点Ａの第１の呼制御装置１０ａからの動作可通知が拠点Ｂの第２の呼制御装置１０ｂへ到達するようになる（ステップ５７）。
【００６５】
この結果、拠点Ｂの第２の呼制御装置１０ｂの監視部１３ｂは、当初、運用系であった拠点Ａの第１の呼制御装置１０ａの障害が復旧したと認識して、運用状態であった呼制御部１２ｂを待機状態にして、運用系であった第２の呼制御装置１０ｂを予備系に切り替える（ステップ５８）。そして、予備系として、拠点Ａの第１の呼制御装置１０ａに動作可通知を送信する（ステップ６０）。なお、拠点Ｂの第２の呼制御装置１０ｂの監視部１３ｂは、予備系に切り替わった時点から、拠点Ｂの各通信端末２０ｂへ動作確認要求を送信しなくなる。
【００６６】
また、拠点Ａの第１の呼制御装置１０ａの監視部１３ｂは、障害発生中も定期的に送っていた動作可通知を拠点Ｂの第２の呼制御装置１０ｂへ送信すると共に（ステップ５７）、拠点Ｂの第２の呼制御装置１０ｂからの動作可通知により（ステップ６０）、この第２の呼制御装置１０ｂが復旧したと認識して、第１の呼制御装置１０ａの設定情報管理部１４ａは、呼サービス設定情報を拠点Ｂの第２の呼制御装置１０ｂへ送信し始める（ステップ６１）。
【００６７】
一方、拠点Ｂの通信端末２０ｂの監視部２５は、今まで運用系であった第２の呼制御装置１０ｂから、一定期間、動作確認要求が送信されてこないことから（ステップ５０ｂ）、拠点Ｂの第２の呼制御装置１０ｂに障害が発生したと認識して、この第２の呼制御装置１０ｂとの接続を解放する（ステップ６２）。
【００６８】
そして、拠点Ｂの各通信端末２０ｂの監視部２５は、呼制御可能な呼制御装置を検索するため、端末自身のＩＰアドレスと共に、検索応答要求をマルチキャストで送信する（ステップ６３）。この検索応答要求に対して、再び、運用系になった第１の呼制御装置１０ａの監視部１３ａは、検索応答要求のあった拠点Ｂの通信端末２０ｂに対して、検索応答と共に第１の呼制御装置１０ａのＩＰアドレスを送信して、現在運用状態にある呼制御装置１０ａを認識させると共に（ステップ６４）、検索応答要求のあった通信端末２０ｂのＩＰアドレスを記憶する（ステップ６８）。検索応答と共に第１の呼制御装置１０ａのＩＰアドレスを受信した通信端末２０ｂの通信インタフェース２１は、このＩＰアドレスを記憶し（ステップ６５）、その後、この運用系になった第１の呼制御装置１０ａとの間で、呼制御通信のための接続処理を行う（ステップ６７）。
【００６９】
以降、図７に示す中継回線に障害が発生する前と同様に、拠点Ａの第１の呼制御装置１０ａは、拠点Ａ，Ｂの通信端末２０ａ，２０ｂに対して、動作確認要求を送信し（ステップ３５ａ，３５ｂ）、拠点Ａ，Ｂの通信端末２０ａ，２０ｂから動作確認応答を受信する（ステップ３６ａ，３６ｂ）。さらに、第１の呼制御装置１０ａは、再び予備系になった第２の呼制御装置１０ｂに動作可通知及び呼サービス設定情報を送信し（ステップ３１，３３）、この第２の呼制御装置１０ｂから動作可通知を受信する（ステップ３２）。
【００７０】
以上のように、本実施形態では、二つの拠点間の中継回線に障害が生じても、各拠点に設けられている呼制御装置が運用系になり、各拠点内での各通信端末相互の呼制御を行うので、中継回線障害による被害を最小限に抑えることができる。また、中継回線に障害が生じて、予備系であった呼制御装置が運用系に切り替わっても、当初から運用系であった呼制御装置から、呼サービス設定情報を取得しているので、各拠点で同じサービスを提供することができる。
【００７１】
なお、本実施形態で、当初、運用系である第１の呼制御装置１０ａに障害が発生した場合には、第１の実施形態と同様に、第２の呼制御装置１０ｂが運用系になり、この第２の呼制御装置１０ｂが各拠点Ａ，Ｂの各通信端末２０ａ，２０ｂの呼制御を行うことになる。従って、本実施形態でも、第１の実施形態と同様の効果を得ることができる。
【００７２】
また、本実施形態では、二つの拠点Ａ，Ｂにそれぞれ呼制御装置１０ａ，１０ｂを設けた例を示したが、本発明は、これに限定されるものではなく、三つ以上の拠点にそれぞれ呼制御装置を設けてもよい。この場合、複数の拠点の各予備系呼制御装置に関して、予め優先順位を定めておき、一つの拠点の運用系呼制御装置に障害が発生すると、この優先順位に従って、複数の予備系のうちの一つが運用系になるようにするとよい。
【００７３】
【発明の効果】
本発明によれば、２台の呼制御装置のうち、運用状態の呼制御装置に障害が生じても、待機状態の呼制御装置が運用状態となって、各通信端末相互の呼制御を行うので、呼制御障害による被害を最小限に抑えることができる。また、２台の呼制御装置相互間で、呼制御可能な状態であるか否かを通信で確認しあっているので、２台の呼制御装置の他に別途、これらを管理する呼制御管理装置が不要になり、装置コストを抑えることができる。
【図面の簡単な説明】
【図１】本発明に係る第１の実施形態における通信システムの機能ブロック図である。
【図２】本発明に係る第１の実施形態における通信システムのシーケンス図である。
【図３】本発明に係る第１の実施形態における通信端末の立ち上がり時からの動作を示すフローチャートである。
【図４】本発明に係る第１の実施形態における呼制御装置の各状態での動作を示す説明図である。
【図５】本発明に係る第２の実施形態における通信システムの回路ブロック図である。
【図６】本発明に係る第２の実施形態における通信システムのシーケンス図（その１）である。
【図７】本発明に係る第２の実施形態における通信システムのシーケンス図（その２）である。
【図８】従来の通信システムの機能ブロック図である。
【符号の説明】
１…ＷＡＮ、２ａ，２ｂ…中継装置、３，１０ａ，１０ｂ…呼制御装置、９，９ａ，９ｂ…ＬＡＮ回線、１１ａ，１１ｂ…通信インタフェース、１２ａ，１２ｂ…呼制御部、１３ａ，１３ｂ…監視部、１４ａ，１４ｂ…設定情報管理部、１５ａ，１５ｂ…記憶部、２０，２０ａ，２０ｂ，２８，２９，２９ａ，２９ｂ…通信端末、２１…通信インタフェース、２２…符号化・複合化部、２５…監視部、２６…記憶部。[0001]
BACKGROUND OF THE INVENTION
  The present inventionA communication terminal that is call-controlled by one of a plurality of call control devices to perform IP packet communication with other communication terminals,thisTheIncluding communication system, AndThe present invention relates to a countermeasure method for call control failure.
[0002]
[Prior art]
Conventional IP packet communication systems include those shown in FIG.
[0003]
This IP packet communication system includes a plurality of communication terminals 7 and 8 that perform IP packet communication, and a call control device 3 that performs call control between the plurality of communication terminals 7 and 8. A plurality of communication terminals 7 and 8 and the call control device 3 are connected by a LAN line 9. Examples of the communication terminals 7 and 8 include an IP telephone, an IP gateway, and an IP / PBX (Private Branch Exchanger) to which a plurality of general telephones are connected.
[0004]
The call control device 3 includes a first call control unit 5a, a second call control unit 5b, and a call control management unit 6 that manages these call control units 5a and 5b in order to perform non-stop call service. And a communication interface 4 for performing IP packet communication. In the call control device 3, if the first call control unit 5a is in an operating state, the second call control unit 5b is in a standby state. At this time, the call control management unit 6 constantly monitors whether or not a failure has occurred in the first call control unit 5a in the operating state, and the call owned by the first call control unit 5b. The service setting information and the call control status information are given to the second call control unit 5b as they are. In other words, when the first call control unit 5a acquires the call service information and the call control state information, the information is dead-copied to the second call control unit 5b almost at the same time. Note that the call service setting information is information related to a call service that can be set by each terminal, for example, various services such as an incoming call transfer service for transferring an incoming call to the terminal itself to another terminal. Call control status information is information relating to the status of each terminal, such as which terminal is busy.
[0005]
In this call control device 3, when a failure occurs in the first call control unit 5a, the call control management unit 6 immediately detects this failure and owns all the information of the first call control unit 5a. The waiting second call control unit 5b is activated to realize a non-stop call service.
[0006]
[Problems to be solved by the invention]
However, in the above prior art, in addition to the first call control unit 5a, a second call control unit 5b as a spare device is provided, and hardware independent of the two call control units 5a and 5b is provided. Therefore, there is a problem that the apparatus cost is increased. In particular, as described above, when the first call control unit 5a acquires the call service setting information and call control state information of the terminal, the call control management unit 6 sends these information to the second call control unit almost simultaneously. In order to make a dead copy in 5b, it is composed of special hardware and is very expensive.
[0007]
The present invention has been made by paying attention to such problems of the prior art, and can suppress a device cost and can cope with a failure in call control, a communication system including the device, and An object is to provide a countermeasure method for a call control failure.
[0008]
[Means for Solving the Problems]
  To achieve the purposeCommunication terminalIs
  A communication terminal that is call-controlled by one of a plurality of call control devices to perform IP packet communication with another communication terminal,
Communication means for performing IP packet communication between the other communication terminal and the plurality of call control devices;
When one call control device of the plurality of call control devices is in an operational state in which call control is possible, and when the other call control device is in a standby state, from the one call control device via the communication means When it is received every certain time that it is in an operational state in which call control is possible, the one call control device in the operational state is monitored, and the fact that it is in an operational state in which call control is possible cannot be received for a certain period of time or more The monitoring means for recognizing that a failure has occurred in the call control by the one call control apparatus, and for causing the communication means to release the call control connection to the one call control apparatus;
  It is characterized by having.
[0009]
  here,The monitoring unit of the communication terminal is unable to receive the call control enabled operation state for a predetermined time or more, and after releasing a call control connection to the one call control device, a plurality of the call control devices Requesting a response from the call control device that is currently in an operational state capable of call control via the communication means.It is preferable.
[0017]
  Here, a communication system for achieving the object is
A first call control device;
A second call control device;
A plurality of communication terminals according to claim 1;
With
The first call control device, the second call control device, and each of the plurality of communication terminals are connected to each other via a line,
The first call control device includes:
Communication means for performing IP packet communication between the plurality of communication terminals and the second call control device, call control means for performing call control of the plurality of communication terminals, and failure in call control by the call control means Is sent to the second call control device when a failure has not occurred and the call control is possible, and there is a failure in the call control by the call control means. Recognizing that it has occurred, the monitoring means for stopping the transmission of the operation enable notification to the second call control device, to put the call control means from the operating state to the standby state,
The second call control device includes:
A communication means for performing IP packet communication between the plurality of communication terminals and the first call control device; a call control means for performing call control of the plurality of communication terminals; When an operation enable notification indicating that the call control is possible is received from one call control device and the operation enable notification cannot be received for a predetermined time or more, it is determined that the first call control device is in a call control disabled state. Monitoring means for activating the call control means in a standby state to put it in an operating state,
When communicating between one communication terminal and another communication terminal among a plurality of communication terminals, the call control means of the first call control device and the call control means of the second call control device Among these, call control is performed by the call control means in the operating state.
  It is characterized by this.
[0018]
  Other to achieve the above purposeThe communication system
A first call control device;
For the first call control device, a LAN ( Local Area network A plurality of communication terminals according to claim 1 (hereinafter referred to as first communication terminals) connected via a line;
For the first call control device, WAN ( Wide Area network A second call control device connected via
For the second call control device, a LAN ( Local Area network A plurality of communication terminals according to claim 1 (hereinafter referred to as second communication terminals) connected via a line;
With
The first call control device includes:
Communication means for performing IP packet communication between the plurality of communication terminals and the second call control device, call control means for performing call control of the plurality of communication terminals, and failure in call control by the call control means Is sent to the second call control device when a failure has not occurred and the call control is possible, and there is a failure in the call control by the call control means. Recognizing that it has occurred, the monitoring means for stopping the transmission of the operation enable notification to the second call control device, to put the call control means from the operating state to the standby state,
The second call control device includes:
A communication means for performing IP packet communication between the plurality of communication terminals and the first call control device; a call control means for performing call control of the plurality of communication terminals; When an operation enable notification indicating that the call control is possible is received from one call control device and the operation enable notification cannot be received for a predetermined time or more, it is determined that the first call control device is in a call control disabled state. Monitoring means for activating the call control means in a standby state to put it in an operating state,
When communicating between any two of the plurality of first communication terminals and the plurality of second communication terminals, the call control means of the first call control device and the Call control is performed by the call control means in the operating state among the call control means of the second call control device.
  It is characterized by this.
[0019]
MaFurther, a countermeasure method for a call control failure to achieve the above-mentioned object is as follows:
  Providing a first call control device and a second call control device capable of IP packet communication with a plurality of communication terminals;
  The first call control device includes:
  A call control step for performing call control of a plurality of the communication terminals;
  Whether or not a failure has occurred in the call control in the call control step is monitored, and when no failure has occurred and the call control is possible, the second call control device can operate at regular intervals. When a notification is sent and it is recognized that a failure has occurred in the call control in the call control step, the transmission of the operation enable notification to the second call control device is stopped and the call control step is operated. A monitoring process for switching from a state to a standby state;
  Run
  The second call control device includes:
  A call control step for performing call control of a plurality of the communication terminals;
  When a notification indicating that the call control is possible is received from the first call control device, and the operation enable notification cannot be received for the predetermined time or more, the first call control device is in a call control disabled state. And the monitoring step of activating the call control step in the standby state to bring it into an operating state;
  Run
Among the first call control device and the second call control device, in the monitoring step of the call control device in which the call control step is in operation, call control is possible for a plurality of the communication terminals. Notify every time that it is in a state,
When the plurality of communication terminals cannot receive the operational state in which the call control is possible for the predetermined time or longer, the call control is currently performed between the first call control device and the second call control device. Request a response from a call control device in a possible operational state,
Among the first call control device and the second call control device, in the monitoring process of the call control device that is currently in an operation state in which the call control is possible, in response to the response requests from the plurality of communication terminals The IP address of the call control device is transmitted to the communication terminal that has transmitted the response request.
  It is characterized by this.
[0021]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, various embodiments of an IP packet communication system according to the present invention will be described with reference to the drawings.
[0022]
First, an IP packet communication system as a first embodiment according to the present invention will be described with reference to FIGS.
[0023]
As shown in FIG. 1, the IP packet communication system according to the present embodiment includes first and second communication terminals 20, 28, and 29 that perform IP packet communication and first and second that perform call control between the plurality of communication terminals. Call control devices 10a and 10b. A plurality of communication terminals 20, 28, 29 and call control devices 10a, 10b are connected to each other by a LAN line 9. In this embodiment, one of the plurality of communication terminals 20, 28 and 29 is the IP gateway 20, and the rest are the IP telephones 28 and 29.
[0024]
Each of the first and second call control devices 10a and 10b includes communication interfaces 11a and 11b for performing IP packet communication, and call control units 12a and 12b for actually performing call control between the communication terminals. A monitoring unit 13a that monitors the states of the call control units 12a and 12b and the other call control devices 10b and 10a, and a setting information management unit 14a that manages setting information related to the call control service of each of the terminals 20, 28, and 29. Storage units 15a and 15b for storing call service setting information, IP addresses of the respective communication terminals, and the like.
[0025]
The monitoring units 13a and 13b can monitor the call control units 12a and 12b and the communication interfaces 11a and 11b, and can operate to indicate that the call control is possible via the communication interfaces 11a and 11b if there is no failure. A notification is sent to the other call control device. In addition, the other call control device receives an operable notification via the communication interfaces 11a and 11b. The monitoring units 13a and 13b are based on the monitoring results of the call control units 12a and 12b and the communication interfaces 11a and 11b and the operable notification from the other call control device, and the call control units 12a and 12b and the setting information management unit 14a, 14b is switched from the standby state to the operational state, or from the operational state to the standby state.
[0026]
In the operational state, the setting information management units 14a and 14b transmit the call service setting information stored in the storage units 15a and 15b to the other call control device via the communication interfaces 11a and 11b. At this time, call service setting information is acquired from the other call control device and registered in the storage units 15a and 15b.
[0027]
Each communication terminal 20, 28, 29 converts a communication interface 21 for performing IP packet communication and an IP packet received by the communication interface 21 into a voice signal and the like, while converting a voice signal and the like into an IP packet. The encoder / decoder 22, the A / D converter 23 that converts the audio signal decoded by the encoder / decoder 22 into an analog signal, and the states of the two call control devices 10 a and 10 b are monitored. And a monitoring unit 25. When the communication terminal is the IP gateway 20, an interface 24 for transmitting / receiving an audio signal or the like to / from the PBX or the like is connected to the A / D converter 23. When the communication terminals are IP telephones 28 and 29, a handset or the like is connected to the A / D converter.
[0028]
Next, the operation of the communication system of the present embodiment described above will be described with reference to FIG. In the figure, by the initial setting, the call control unit 11a of the first call control device 10a is in an operating state, the first call control device 10a functions as an active system, and the call of the second call control device 10b. It is assumed that the control unit 11b is set in a standby state so that the second call control device 10b functions as a standby system. Further, it is assumed that the communication terminal 20 is in a connection operation with respect to the first call control device 10a working as an active system.
[0029]
The monitoring unit 13a of the first call control device 10a, which is the active system, periodically monitors its own call control unit 12a and the communication interface 11a to confirm that the call control is possible, and the communication interface 11a. Then, an operation enable notification is transmitted to the second call control device 10b via the LAN line 9 (step 1). In addition, the monitoring unit 13b of the second call control device 10b, which is a standby system, also periodically transmits an operation enable notification to the first call control device 10a (step 2). In addition, the setting information management unit 14a of the first call control device 10a periodically transmits call service setting information of each communication terminal stored in the storage unit 15a via the communication interface 11a and the LAN line 9. Transmit to the second call control device 10b (step 3). Note that the call service setting information of each communication terminal 20 is set by an operation by a user or the like in each communication terminal 20, and this information is set information management of the call control device 10a by call control communication (step 4) described later. To the unit 14a.
[0030]
When the communication terminal 20 makes a call with another communication terminal, call control communication is performed with the call control device 10a that the communication terminal 20 recognizes as an active system, that is, the communication terminal 20 Call control device 10a is requested to perform call control between the communication terminal and another communication terminal (step 4). When a communication line with another communication terminal is established by this call control communication, a call can be made with the other communication terminal.
[0031]
The monitoring unit 13a of the active call control device 10a periodically monitors its own call control unit 12a and the communication interface 11a and confirms that the call control is possible, as in the case of transmitting the operation enable notification. Then, it indicates that the call control is possible via the communication interface 11a and the LAN line 9, and transmits an operation confirmation request for requesting a response to each communication terminal 20 (step 5). When receiving the operation confirmation request, the monitoring unit 25 of the communication terminal 20 recognizes that the operation confirmation request source is the active system. Then, as an answer to the operation confirmation request, an operation confirmation response is transmitted to the active call control device 10a (step 6).
In other words, the active call control device 10a periodically transmits an operation enable notification and call service setting information to the standby call control device 10b (steps 1 and 3), for example, every 5 seconds (steps 1 and 3). The device 10b periodically transmits an operation enable notification to the active call control device 10a (step 2). Further, the active call control device 10a periodically transmits an operation confirmation request to each communication terminal 20 (step 5).
[0032]
As described above, whether the two call control devices 10a and 10b transmit the operation ready notification to the other call control devices 10b and 10a, so that the other call control device is in a state in which call control is possible. You can recognize whether or not. Further, the call service setting information can be shared by the active call control device 10a periodically transmitting the call service setting information to the standby call control device 20b. In addition, when the active call control device 10a periodically transmits an operation check request, each terminal 10 can recognize which call control device is currently active.
[0033]
When a failure occurs in the call control unit 12a or the communication interface 11a of the active call control device 10a (step 7), the monitoring unit 13a of the active call control device 10a recognizes this failure, and the current standby call control device. The operation permission notification to 10b and the operation confirmation request to each communication terminal are stopped, the call control unit is set in a standby state, and the standby system is switched (step 8).
[0034]
Since the monitoring unit 13b of the second call control device 10b, which is the standby system, initially does not receive an operation permission notification from the first call control device 10a, which is the active system, for the first period, Recognizing that a failure has occurred in the call control device 10a, the call control unit 12b, which has been in a standby state, is put into an operation state, and the second call control device 10b is switched to the operation system (step 9).
[0035]
In addition, since the monitoring unit 25 of each communication terminal 20 does not receive an operation confirmation request for a certain period from the first call control device 10a that was initially active, the first call control device 10a. Recognizing that a failure has occurred, the connection with the first call control device 10a is released (step 10).
[0036]
The monitoring unit 25 of each communication terminal 20 transmits a search response request by multicast together with the IP address of the terminal itself in order to search for a call control device capable of call control (step 11). In response to this search response request, the first call control device 10b switched to the standby system does not respond, and the monitoring unit 13b of the second call control device 10b switched to the active system communicates with the search response request. The IP address of the second call control device 10b is transmitted to the terminal 20 together with the search response so that the call control device 10b currently in operation is recognized (step 12), and the communication terminal that requested the search response 20 IP addresses are stored (step 15). The communication interface 21 of the communication terminal 20 that has received the IP address of the second call control device 10b together with the search response stores this IP address (step 13), and then the second call control device that has become the active system. Connection processing for call control communication is performed with 10b (step 14).
[0037]
The monitoring unit 13b of the second call control device 10b that has been switched to the active system periodically performs its own call control unit 12b and communication interface 11b in the same manner as when the first call control device 10a is the active system. Is confirmed to be in a call controllable state, an operation ready notification is transmitted to the first call control device 10a as a standby system (step 21), and an operation confirmation request is transmitted to each communication terminal. (Step 25). In response to this operation confirmation request, each communication terminal 20 returns an operation confirmation response to the second call control device 10b that is currently in operation (step 26). The setting information management unit 14b of the second call control device 10b transmits call service setting information to the first call control device 10a (step 23). The monitoring unit 13a of the first call control device 10a, which is a standby system, monitors its own call control unit 12a and the communication interface 11a. Operational notification is periodically transmitted to the call control device 10b.
[0038]
When the communication terminal 20 makes a call with another communication terminal, as in step 4, the call control device recognized by the monitoring unit of the communication terminal 20 as the active system, in this case, the second call Call control communication is performed with the control device 10b (step 24). When a communication line with another communication terminal is established by this call control communication, a call can be made with the other communication terminal.
[0039]
Note that the processing in steps 11 to 14 described above is performed as initial processing so that each communication terminal 20 recognizes the active call control device even when each communication terminal 20 is started up. Specifically, as shown in the flowchart of FIG. 3, first, the monitoring unit 25 of the communication terminal 20 transmits a search response request together with the IP address of the terminal by multicast in order to search for a call control device capable of call control. (Step 11). Subsequently, the monitoring unit 25 waits for reception of a search response from the active call control device in response to this search response request (step 12). When this search response is received, the monitoring unit 25 is sent together with the search response. The IP address of the active call control device is registered in the storage unit 26 (step 13). Further, the monitoring unit 25 causes the communication interface 21 to execute a connection process for performing call control communication with the active call control device (step 14).
[0040]
Thereafter, when the communication terminal 20 makes a call with another communication terminal, call control communication is performed with the call control device stored as the active system in the storage unit 26 of the communication terminal 20 (step). 24). Further, the monitoring unit 25 determines whether or not an operation check request from the active call control device is periodically received (step 25). If the operation check request cannot be received, the monitoring unit 25 returns to step 11; If the operation confirmation request has been received, an operation confirmation response is sent to the active call control device (step 26).
[0041]
Here, the operation of each call control device will be described together with FIG.
[0042]
If there is no failure, the active call control device periodically sends an operational notification and call service setting information to the standby call control device, regardless of whether or not there is a failure in the standby call control device. To do. Also, an operation confirmation request is transmitted to the communication terminal, a search response is returned in response to the search response request, and a call service instruction at the time of call control connection is given.
[0043]
When a failure occurs in the active call control device, this active system is transferred to the standby system, and the standby system is moved to the active system, the call control device moved from the standby system to the active system is changed from the active system to the standby system. Regardless of whether the call control device has a fault or not, the operation control notification and call service setting information are periodically transmitted to the transferred call control device. Also, an operation confirmation request is transmitted to the communication terminal, a search response is returned in response to the search response request, and a call service instruction at the time of call control connection is given.
[0044]
When there is no failure, the standby call control device periodically transmits an operation enable notification to the active call control device. The transmission of call service setting information to the active call control device, the transmission of an operation confirmation request to the communication terminal, the search response to the search response request from the communication terminal, and the call service instruction at the time of call control connection are all active call control. It is performed by the device, and the standby call control device is not performed.
[0045]
When a failure occurs in the active call control device, and this active system is transferred to the standby system, the call control device that has been transferred from the active system to the standby system receives an operation enable notification and call service setting information for the active call control device. Do not send. Furthermore, the transmission of an operation confirmation request to the communication terminal, the search response to the search response request from the communication terminal, and the call service instruction at the time of call control connection are not performed.
[0046]
As described above, in this embodiment, even if a failure occurs in the active call control device 10a among the two call control devices 10a and 10b, the standby call control device 10b becomes the active system, and each communication Since terminal-to-terminal call control is performed, damage due to call control failure can be minimized. In addition, since the two call control devices 10a and 10b confirm whether or not the call control is possible by communication, in addition to the two call control devices 10a and 10b, these are separately provided. The call control management device for managing the device becomes unnecessary, and the device cost can be reduced.
[0047]
Next, an IP packet communication system as a second embodiment according to the present invention will be described with reference to FIGS.
[0048]
In the IP packet communication system of this embodiment, as shown in FIG. 5, two communication bases A and B are connected via a WAN (Wide Area Network) 1 that is an IP network and relay devices 2a and 2b such as routers. It is what has been. Each of the communication bases A and B includes call control devices 10a and 10b, the above-described relay devices 2a and 2b, and a plurality of communication terminals 20a, 29a, 20b, and 29b. The call control devices 10a and 10b, the relay devices 2a and 2b, and the plurality of terminals 20a, 29a, 20b, and 29b are connected to each other by LAN lines 9a and 9b. In other words, in the first embodiment, two call control devices and a plurality of communication terminals are provided in a certain base. However, in the first embodiment, two communication bases are respectively provided via the WAN 1. A call control device for each unit and a plurality of communication terminals are provided.
[0049]
As in the first embodiment, the call control devices 10a and 10b at the respective bases A and B are calls that actually perform call control between the communication interfaces 11a and 11b for performing IP packet communication and the communication terminals. Control units 12a and 12b, monitoring units 13a and 13b that monitor the states of the call control units 12a and 12b and the other call control device, and a setting information management unit 14a that manages setting information related to the call control service of each terminal. 14b and storage units 15a and 15b for storing call service setting information and the like.
[0050]
Similarly to the first embodiment, the communication terminals 20a and 20b of the respective bases A and B also use the communication interface 21 for performing IP packet communication and the IP packet received by the communication interface 21 as a voice signal or the like. An encoding / decoding unit 22 that converts an audio signal or the like into an IP packet, and an A / D converter 23 that converts the audio signal decoded by the encoding / decoding unit 22 into an analog signal, , A monitoring unit 25 for monitoring the states of the two call control devices, and a storage unit 26.
[0051]
Next, the operation of the communication system of the present embodiment described above will be described with reference to FIG. In the figure, it is assumed that the first call control device 10a at the site A functions as an active system and the second call control device 10b at the site B functions as a standby system by the initial setting. . In addition, it is assumed that the communication terminals 20a and 20b at the respective bases A and B are connected to the first call control device 10a working as an active system.
[0052]
As in the first embodiment, the monitoring unit 13a of the first call control device 10a, which is the active system, notifies the operation enable notification and the call of each communication terminal via the communication interface 11a, the relay devices 2a and 2b, and the WAN1. The service setting information is transmitted to the second call control device 10b which is a standby system (steps 31 and 33). In addition, the monitoring unit 13b of the second call control device 10b, which is a standby system, also periodically sends an operation enable notification to the first call control device 10a in the same manner as described above (step 32).
[0053]
When the communication terminals 20a and 20b at the bases A and B make a call with the other communication terminals 20b and 20a, a call is made with the call control device 10a that the communication terminals 20a and 20b recognize as an active system. Control communication is performed (steps 34a and 34b).
[0054]
The monitoring unit 13a of the active call control device 10a at the site A transmits an operation confirmation request to the communication terminals 20a and 20b at the sites A and B (steps 35a and 35b). When receiving the operation confirmation request, the monitoring units 13a and 13b of the communication terminals 20a and 20b at the respective bases A and B recognize that the operation confirmation request source is an active system and operate as a response to the operation confirmation request. A confirmation response is transmitted to the active call control device 10a (steps 36a and 36b).
[0055]
That is, the processes from step 31 to 36b are the same as the processes from step 1 to 6 in the first embodiment.
[0056]
When a failure occurs in the relay line between the bases A and B (step 37), the monitoring unit 13a of the active call control device 10a does not recognize the failure of its own call control unit 12a. First, an operation permission notification is transmitted to the standby call control device 10b at the site B (step 38), and an operation confirmation request is transmitted to the communication terminals 20a and 20b at the sites A and B (steps 40a and 40b). In addition, the monitoring unit 13b of the standby call control device 10b at the site B also transmits an operation confirmation request to the active call control device 10a at the site A (step 39). However, since a failure has occurred in the relay line between the bases A and B, the operation enable notification and the operation confirmation request from the active call control device 10a of the base A to the base B do not reach the base B (step 38). , Step 40b), and the notification of the availability of operation from the standby call control device 10b at the site B to the site A does not reach the site A (step 39).
[0057]
Since the active call control device 10a at the site A cannot receive the operation enable notification from the standby call control device at the site B, it recognizes that a failure has occurred at the site B, and thereafter only the communication terminal 20a at the site A. Then, an operation confirmation request is transmitted (step 40a), and an operation confirmation response is received from this terminal 20a (step 41a). Furthermore, call control communication is performed only with the communication terminal at the site A (step 42a). However, the operation confirmation request is transmitted to the base B periodically thereafter (steps 38, 38,...).
[0058]
On the other hand, since the monitoring unit 13b of the standby call control device 10b at the site B does not receive an operation permission notification from the active call control device 10a at the site A for a certain period (step 38), the operation of the site A Recognizing that a failure has occurred in the system call control device 10a, the call control unit 12b, which has been in a standby state, is put into an operation state, and the second call control device 10b, which is a standby system, is switched to the operation system (step 43). ).
[0059]
In addition, since the monitoring unit 25 of each communication terminal 20b at the site B does not receive an operation confirmation request for a certain period from the first call control device 20a that was initially active (step 40b), the site Recognizing that a failure has occurred in the first call control apparatus 10a of A, the connection with the first call control apparatus 10a is released (step 41).
[0060]
Then, the monitoring unit 25 of each communication terminal 20b at the base B transmits a search response request by multicast together with the IP address of the terminal itself in order to search for a call control device capable of call control (step 44). In response to this search response request, the monitoring unit 13b of the second call control device 10b switched to the active system sends the second call control together with the search response to the communication terminal 20b of the base B that has made the search response request. The IP address of the device 10b is transmitted to recognize the call control device 10b that is currently in operation (step 45), and the IP address of the communication terminal 20b that requested the search response is stored (step 48). The communication interface 21 of the communication terminal 20b that has received the IP address of the second call control device 10b together with the search response stores the IP address in the storage unit 25 (step 46), and then the second interface that has become the active system. Connection processing for call control communication is performed with the call control device 10b (step 47).
[0061]
The monitoring unit 13b of the second call control device 10b that has been switched to the active system periodically performs its own call control unit 12b and communication interface 11b in the same manner as when the first call control device 10a is the active system. Is confirmed to be in a call controllable state, an operation enable notification is transmitted to the first call control device 10a at the site A (step 52), and an operation confirmation request is sent to each communication terminal 20b at the site B. Is transmitted (step 50b). In response to this operation confirmation request, each communication terminal 20b at the site B returns an operation confirmation response (step 51b).
[0062]
As described above, when a failure occurs in the trunk line, the first call control device 10a at the site A maintains the active system, but only as a call control device for each communication terminal 20a at the site A. The second call control device 10b of the base B that was initially a standby system functions as a call control device only for each communication terminal 20b of the base B, although it is switched to the active system. That is, when a failure occurs in the relay line, the call control device at each site becomes the active call control device at each site.
[0063]
Next, the operation when the failure of the trunk line is recovered will be described with reference to FIG.
[0064]
When the failure of the trunk line is recovered (step 55), the operation ready notification from the second call control device 10b at the site B reaches the first call control device 10a at the site A (step 56). Similarly, the notification that the operation is possible from the first call control device 10a at the site A reaches the second call control device 10b at the site B (step 57).
[0065]
As a result, the monitoring unit 13b of the second call control device 10b at the base B recognizes that the failure of the first call control device 10a at the base A, which was the active system, has been recovered, and is in an operating state. Then, the call control unit 12b is set in the standby state, and the second call control device 10b, which is the active system, is switched to the standby system (step 58). Then, as a standby system, an operation enable notification is transmitted to the first call control device 10a at the site A (step 60). Note that the monitoring unit 13b of the second call control device 10b at the site B does not transmit an operation confirmation request to each communication terminal 20b at the site B from the time of switching to the standby system.
[0066]
In addition, the monitoring unit 13b of the first call control device 10a at the site A transmits an operation enable notification that has been periodically transmitted even during the occurrence of a failure to the second call control device 10b at the site B (step 57). When the operation is notified from the second call control device 10b at the site B (step 60), the second call control device 10b recognizes that the second call control device 10b has recovered, and the setting information management unit of the first call control device 10a 14a starts transmitting the call service setting information to the second call control device 10b at the site B (step 61).
[0067]
On the other hand, since the monitoring unit 25 of the communication terminal 20b at the site B does not receive an operation confirmation request for a certain period from the second call control device 10b that has been the active system until now (step 50b), the site B Recognizing that a failure has occurred in the second call control device 10b, the connection with the second call control device 10b is released (step 62).
[0068]
Then, the monitoring unit 25 of each communication terminal 20b at the base B transmits a search response request by multicast together with the IP address of the terminal itself in order to search for a call control device capable of call control (step 63). In response to this search response request, the monitoring unit 13a of the first call control device 10a that has become the active system again sends the first response together with the search response to the communication terminal 20b of the base B that has made the search response request. The IP address of the call control device 10a is transmitted to recognize the call control device 10a that is currently in operation (step 64), and the IP address of the communication terminal 20b that requested the search response is stored (step 68). The communication interface 21 of the communication terminal 20b that has received the IP address of the first call control device 10a together with the search response stores this IP address (step 65), and then the first call control device that has become the active system. Connection processing for call control communication is performed with 10a (step 67).
[0069]
Thereafter, the first call control device 10a at the site A transmits an operation check request to the communication terminals 20a and 20b at the sites A and B in the same manner as before the failure of the trunk line shown in FIG. (Steps 35a and 35b), operation confirmation responses are received from the communication terminals 20a and 20b at the bases A and B (Steps 36a and 36b). Further, the first call control device 10a transmits the operation enable notification and the call service setting information to the second call control device 10b which has become the standby system again (steps 31 and 33), and this second call control device. An operation enable notification is received from 10b (step 32).
[0070]
As described above, in this embodiment, even if a failure occurs in a relay line between two bases, the call control device provided at each base becomes an active system, and each communication terminal in each base Because call control is performed, damage caused by a trunk line failure can be minimized. Also, even if a failure occurs in the trunk line and the call control device that was the standby system is switched to the active system, the call service setting information is acquired from the call control device that was the active system from the beginning. The same service can be provided at the base.
[0071]
In the present embodiment, when a failure occurs in the first call control device 10a, which is the active system, the second call control device 10b becomes the active system as in the first embodiment. The second call control device 10b performs call control of the communication terminals 20a and 20b at the bases A and B. Therefore, also in this embodiment, the same effect as that of the first embodiment can be obtained.
[0072]
Moreover, in this embodiment, although the example which provided the call control apparatuses 10a and 10b in the two bases A and B was shown, this invention is not limited to this, respectively. A call control device may be provided. In this case, priorities are determined in advance for the standby call control devices at a plurality of bases, and when a failure occurs in the active call control device at one base, One should be active.
[0073]
【The invention's effect】
According to the present invention, even if a failure occurs in the active call control device of the two call control devices, the call control device in the standby state becomes the active state and performs call control between the communication terminals. Therefore, damage due to call control failure can be minimized. In addition, since it is confirmed by communication whether or not call control is possible between the two call control devices, in addition to the two call control devices, call control management for managing these separately. An apparatus becomes unnecessary, and the apparatus cost can be suppressed.
[Brief description of the drawings]
FIG. 1 is a functional block diagram of a communication system in a first embodiment according to the present invention.
FIG. 2 is a sequence diagram of the communication system in the first embodiment according to the present invention.
FIG. 3 is a flowchart showing the operation of the communication terminal in the first embodiment according to the present invention from the start-up time.
FIG. 4 is an explanatory diagram showing an operation in each state of the call control device according to the first embodiment of the present invention.
FIG. 5 is a circuit block diagram of a communication system in a second embodiment according to the present invention.
FIG. 6 is a sequence diagram (No. 1) of a communication system according to a second embodiment of the present invention.
FIG. 7 is a sequence diagram (No. 2) of the communication system in the second embodiment according to the present invention.
FIG. 8 is a functional block diagram of a conventional communication system.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... WAN, 2a, 2b ... Relay apparatus, 3, 10a, 10b ... Call control apparatus, 9, 9a, 9b ... LAN line, 11a, 11b ... Communication interface, 12a, 12b ... Call control part, 13a, 13b ... Monitoring 14a, 14b ... setting information management unit, 15a, 15b ... storage unit, 20, 20a, 20b, 28, 29, 29a, 29b ... communication terminal, 21 ... communication interface, 22 ... encoding / decoding unit, 25 ... monitoring unit, 26 ... storage unit.

Claims

A communication terminal that is call-controlled by one of a plurality of call control devices to perform IP packet communication with another communication terminal,
Communication means for performing IP packet communication between the other communication terminal and the plurality of call control devices;
When one call control device of the plurality of call control devices is in an operational state in which call control is possible, and when the other call control device is in a standby state, from the one call control device via the communication means When it is received every certain time that it is in an operational state in which call control is possible, the one call control device in the operational state is monitored, and the fact that it is in an operational state in which call control is possible cannot be received for a certain period of time or more the recognizes the call control according to the one of the call control device has failed, a monitoring means for a call control connection Ru is released to the communication means to said first call control apparatus,
A communication terminal comprising:

The communication terminal according to claim 1 ,
The monitoring means is unable to receive the call control enabled operation state for a certain period of time, and after releasing a call control connection to the one call control device, among the plurality of call control devices, Requesting a response from the call control device in the operation state capable of call control via the communication means,
A communication terminal characterized by that.

A first call control equipment,
A second call control equipment,
A plurality of communication terminals according to claim 1 ;
With
The first call control device, the second call control device, and each of the plurality of communication terminals are connected to each other via a line,
The first call control device includes:
Communication means for performing IP packet communication between the plurality of communication terminals and the second call control device, call control means for performing call control of the plurality of communication terminals, and failure in call control by the call control means Is sent to the second call control device when a failure has not occurred and the call control is possible, and there is a failure in the call control by the call control means. Recognizing that it has occurred, the monitoring means for stopping the transmission of the operation enable notification to the second call control device, to put the call control means from the operating state to the standby state,
The second call control device includes:
A communication means for performing IP packet communication between the plurality of communication terminals and the first call control device; a call control means for performing call control of the plurality of communication terminals; When an operation enable notification indicating that the call control is possible is received from one call control device and the operation enable notification cannot be received for a predetermined time or more, it is determined that the first call control device is in a call control disabled state. Monitoring means for activating the call control means in a standby state to put it in an operating state,
When communicating between one communication terminal and another communication terminal among a plurality of communication terminals, the call control means of the first call control device and the call control means of the second call control device Among these, call control is performed by the call control means in the operating state.
A communication system characterized by the above.

A first call control equipment,
A plurality of communication terminals (hereinafter referred to as first communication terminals) according to claim 1 , connected to the first call control device via a LAN (Local Area Network) line,
To the first call control apparatus, and the second call control equipment that is connected via a WAN (Wide Area network),
A plurality of communication terminals (hereinafter referred to as second communication terminals) according to claim 1 , connected to the second call control device via a LAN (Local Area Network) line,
With
The first call control device includes:
Communication means for performing IP packet communication between the plurality of communication terminals and the second call control device, call control means for performing call control of the plurality of communication terminals, and failure in call control by the call control means Is sent to the second call control device when a failure has not occurred and the call control is possible, and there is a failure in the call control by the call control means. Recognizing that it has occurred, the monitoring means for stopping the transmission of the operation enable notification to the second call control device, to put the call control means from the operating state to the standby state,
The second call control device includes:
A communication means for performing IP packet communication between the plurality of communication terminals and the first call control device; a call control means for performing call control of the plurality of communication terminals; When an operation enable notification indicating that the call control is possible is received from one call control device and the operation enable notification cannot be received for a predetermined time or more, it is determined that the first call control device is in a call control disabled state. Monitoring means for activating the call control means in a standby state to put it in an operating state,
When communicating between any two of the plurality of first communication terminals and the plurality of second communication terminals, the call control means of the first call control device and the Call control is performed by the call control means in the operating state among the call control means of the second call control device.
A communication system characterized by the above.

The communication system according to any one of claims 3 and 4 ,
Of the first call control device and the second call control device, the monitoring means of the call control device in which the call control means is in operation is connected to a plurality of the communication terminals via the communication means. On the other hand, it is notified at regular intervals that the call control is possible,
When the monitoring means of the plurality of communication terminals cannot receive the operational state in which the call control is possible for the predetermined time or longer, the monitoring means of the first call control device and the second call control device And requesting a response from the call control device in the operational state capable of controlling the call,
Of the first call control device and the second call control device, the monitoring means of the call control device that is currently in an operational state capable of call control responds to the response requests from the plurality of communication terminals. On the other hand, the IP address of the call control device is transmitted to the communication terminal that has transmitted the response request.
A communication system characterized by the above.

In a countermeasure method for a call control failure between a plurality of communication terminals performing IP packet communication,
A first call control device and a second call control device capable of IP packet communication with a plurality of communication terminals;
The first call control device includes:
A call control step for performing call control of a plurality of the communication terminals;
Whether or not a failure has occurred in the call control in the call control step is monitored, and when the failure has not occurred and the call control is possible, the second call control device can operate at regular intervals. When a notification is sent and it is recognized that a failure has occurred in the call control in the call control process, the transmission of the operation enable notification to the second call control device is stopped and the call control process is operated. A monitoring process for switching from a state to a standby state;
Run
The second call control device includes:
A call control step for performing call control of a plurality of the communication terminals;
When a notification indicating that the call control is possible is received from the first call control device, and the operation enable notification cannot be received for the predetermined time or longer, the first call control device is in a call control disabled state. A monitoring step of activating the call control step in the standby state to bring it into an operating state;
Run
Among the first call control device and the second call control device, in the monitoring step of the call control device in which the call control step is in operation, call control is possible for a plurality of the communication terminals. Notify every time that it is in a state,
When the plurality of communication terminals cannot receive the operational state in which the call control is possible for the predetermined time or longer, the call control is currently performed between the first call control device and the second call control device. Request a response from a call control device in a possible operational state,
Among the first call control device and the second call control device, in the monitoring process of the call control device that is currently in an operation state in which the call control is possible, in response to the response requests from the plurality of communication terminals The IP address of the call control device is transmitted to the communication terminal that has transmitted the response request.
Call control failure countermeasure method characterized by the above.