Telecommunications – Transmitter and receiver at same station – Radiotelephone equipment detail
Reexamination Certificate
1998-12-28
2001-07-03
Bost, Dwayne (Department: 2681)
Telecommunications
Transmitter and receiver at same station
Radiotelephone equipment detail
C455S462000, C455S555000
Reexamination Certificate
active
06256512
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Technical Field
The present invention relates generally to mobile-to-private branch exchange (PBX) telecommunications and in particular to delivering calls from an originating mobile switching center (MSC-O) serving a calling mobile subscriber to a called subscriber's land-line unit by dialing an extension within a PBX. Still more particularly, the present invention relates to employing existing message definitions to obtain a temporary local directory number (TLDN) to facilitate call delivery from the MSC-O to the called PBX extension.
2. Description of the Related Art
Private branch exchanges (PBXs), often referred to interchangeably as private, automatic branch exchanges (PABXs), are commonly employed by enterprises including hotels, large businesses, and government offices to provide external communications access to and from individual enterprise employees. A PBX typically includes a private switch, usually on the enterprise's premises, connected to a common group of lines or trunk circuits running from one or more central offices to provide communications service to a number of individual phones. Originally, PBXs required an operator to place any external calls and to connect incoming calls from the public telephone network to a particular PBX extension. Later, connection to outside lines was made automatic in response to dialing “9” or some other digit (often “0” in Europe), resulting in PABXs. Virtually all PBXs in North America are PABXs, where the terms are utilized interchangeably; however operator-assisted PBXs are still employed outside North America.
Within a PBX, calling parties may usually simply dial a three- or four-digit extension to connect to a called party also within the PBX. With the recent explosion of mobile unit usage by enterprise employees, many enterprises wish to extend support for three- or four-digit dialing for their employees' mobile units, a service often referred to as creating a “virtual private network.” However, current solutions for allowing a mobile unit to dial an extension on a PBX rely on the PBX supporting direct inward dialing (DID), which provides the ability for a caller outside the PBX to call an internal extension without having to pass through an operator or attendant. The dialed extension digits are prefixed with sufficient digits to create a public switched telephone network (PSTN) translatable number which is utilized to route the call from the serving mobile switching center to the PBX. This technique does not work if the PBX or the PSTN switching center to which the PBX is connected does not support direct inward dialing, which is commonly the case in South America and many developing countries.
It would be desirable, therefore, to provide a mechanism allowing wireless infrastructure to support virtual private network service from a mobile phone when the associated PBX or PSTN switching center to which the PBX is connected does not support direct inward dialing.
SUMMARY OF THE INVENTION
It is therefore one object of the present invention to provide an improved method and apparatus for mobile-to-private branch exchange telecommunications.
It is another object of the present invention to provide a method and apparatus of delivering calls from a calling subscriber's mobile unit to the called subscriber's land-line unit by dialing an extension within a private branch exchange.
It is yet another object of the present invention to provide a method and apparatus for employing existing message definitions to utilize a temporary local directory number (TLDN) to facilitate call delivery from the calling subscriber's mobile unit dialing an extension within a private branch exchange.
The foregoing objects are achieved as is now described. Wireless calls to a private branch exchange (PBX) which does not support direct inward dialing—either due to limitations of the PBX itself or due to limitations of the PSTN to which the PBX is connected—are routed by means of an adjunct mobile switching center (MSC-A). An originating mobile switching center (MSC-O) serving the mobile unit which places the call by dialing the (typically) three- or four-digit PBX extension sends the dialed extension digits to the home location register (HLR) or service control point (SCP) via an ANSI-
41
origination request (ORREQ) signaling message. The HLR or SCP transmits an ANSI-
41
routing request (ROUTREQ) signaling message to the MSC-A requesting a temporary local directory number which will be used for connecting the call. The HLR relays the PBX extension number (which may be prefixed by “steering” digits that are used by the MSC-A to select the trunk group that connects the MSC-A to the PBX) that were received in the ORREQ message to the MSC-A via the ROUTREQ message. The MSC-A assigns a TLDN to the call and, when the call arrives, connects the call to the PBX and sends the extension to the PBX via trunk signaling. The PBX then routes the call in accordance with known methods. The invention thus allows a mobile unit to function as a PBX extension even if the PBX or the public telephone switch to which the PBX is connected to do not support direct inward dialing, providing virtual private network services.
The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description.
REFERENCES:
patent: 5506887 (1996-04-01), Emery et al.
patent: 5594777 (1997-01-01), Makkonen et al.
patent: 6014377 (2000-01-01), Gillespie
patent: 6029067 (2000-02-01), Pfundstein
Bost Dwayne
Bracewell & Patterson L.L.P.
Crane John D.
Nortel Networks Limited
Vuong Quochien B.
LandOfFree
Mobile access to a PBX via a TLDN does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Mobile access to a PBX via a TLDN, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Mobile access to a PBX via a TLDN will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2450267