The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 23, 2002
Filed:
Dec. 09, 1999
Michel Thibon, Savigny sur Orge, FR;
Sandrine Millet, Paris, FR;
Erlé De Pillot, Paris, FR;
Ian D. Sinclair, Belleville, CA;
Cuthbert C. Cheung, Belleville, CA;
Aline Gateau, Vincennes, FR;
Nortel Networks Corporation, Montreal, CA;
Abstract
Methods and apparatus are described for maintaining established local calls at an access module in case of change of the call control for a distributed PBX over a communications network, e.g. WAN or LAN, especially an IP network. In accordance with a first main embodiment, the system is composed of one Call Server controlling the call processing of other PBX access modules in a normal situation. These access modules have the ability to operate in Stand Alone or Survival mode if the link to the Call Server is down for any reason. In a second main embodiment, two call servers may be used, an active call server and a hot-standby server. The active call server controls the call processing of the access modules. In case the link between one access module and the active call server fails, the hot-standby Call Server can take over the control of the access module. Therefore, each module can operate in normal mode of the active call server or in normal mode of the hot-standby call server or, as an alternative to either of these, in stand alone or survival mode.