US 5,892,821 A · Virtual wide area centrex

Abstract

A method is disclosed which brings together a combination of special IN features and techniques to allow Centrex stations supported by a plurality of central office switching systems, each at different locations, to function from the customer's perspective as though they were served by a single central office switch. The key to Virtual Wide Area Centrex is a total separation of the telephone numbers seen and used by customers (Customer Number Address--CNA) from the telephone numbers used internally by the network for call routing purposes (Network Node Address--NNA), such that there are two separate and distinct numbering plan domains. A central database, interconnected with each of the Centrex switches, maintains the mapping between CNA and NNA. This database is called upon, as required, to do both forward and reverse translations--i.e., from CNAs to NNA and vice-versa. The net result is that CNAs identify people (e.g., a customer's specific employees and agents) whereas NNAs identify locations (e.g., offices and conference rooms). This permits an environment in which individuals may move from one physical location to another, regardless of the serving central office switch, while keeping their CNA and their network access privileges.

Claims16

Dependent claims

A method of configuring a telephone network for providing Wide Area Centrex services to a number of customer sites having a plurality of telephone network devices, said telephone network having a number of telephone switching offices equipped with SSPs (Service Switching Points) operating with AIN (Advanced Intelligent Network) application software for providing Centrex functionality to said telephone network devices at said customer sites, comprising the steps of:

a) assigning, as a switch resident datafill, a network node address (NNA) to each telephone network device used at said customer sites requiring Centrex functionality;
b) assigning a customer network address (CNA) to each of said telephone network devices, each assigned CNA having a corresponding NNA;
c) assigning, as a switch resident datafill, a Business Group ID (BGID) to each of said telephone network devices to enable a Centrex subscriber using said telephone network device to reach another telephone network device in one of said customer sites using abbreviated dialing of said CNA;
and
d) providing, to each of said SSPs, access to a number translation database table to provide when requested by said SSPs a translation of a CNA to a corresponding NNA and of a NNA to a corresponding CNA when Centrex and Public Switched Telephone Network (PSTN) calls are received and initiated from and to one of said telephone network devices.

2 more elements

A method of providing Wide Area Centrex services to a number of customer sites having a plurality of telephone network devices, said telephone network having a number of telephone switching offices equipped with SSPs (Service Switching Points) operating with AIN (Advanced Intelligent Network) application software for providing Centrex functionality to said telephone network devices at said customer sites, comprising the steps of:

a) assigning, as a switch resident datafill, a network node address (NNA) to each telephone network device used at said customer sites requiring Centrex functionality;
b) assigning a customer network address (CNA) to each of said telephone network devices, each assigned CNA having a corresponding NNA;
c) assigning, as a switch resident datafill, a Business Group ID (BGID) to each of said telephone network devices to enable a Centrex subscriber using said telephone network device to reach another telephone network device in one of said customer sites using abbreviated dialing of said CNA;
d) providing, to each of said SSPs, access to a number translation database table to provide when requested by said SSPs a translation of a CNA to a corresponding NNA and of a NNA to a corresponding CNA;
e) receiving at an SSP of a first customer site a call having a number of digits sent from a calling station;
f) identifying from the dialed digits an internal Centrex call and formulating a Transaction Capabilities Application Part (TCAP) query message appropriate to the AIN trigger used, containing the received digits;
g) transmitting the TCAP message from the SSP of the first customer site to a remotely located SCP, containing said number translation table, via a common transport facility;
h) pre-translating at the SCP the called number to determine how to route the call to any one of the said customer sites served with Centrex type services;
i) formulating a TCAP response message at the SCP containing the NNA associated with said CNA;
j) transmitting the formulated message to the SSP of the first customer site to instruct the telephone network how to complete the call;
and
k) translating the switch-supplied NNA of the calling station to a CNA such that Centrex type terminating station features can be maintained at each customer site.

9 more elements

A telephone network for providing Wide Area Centrex services, having a plurality of Centrex switching offices equipped with Service Switching Points (SSPs) operating with Advanced Intelligent Network (AIN) application software, said network having a switching office for providing Centrex functionality to a number of customer sites, each served by separate switching offices, comprising:

a Service Control Point (SCP) connected to each switching office and having a number translation database containing customer network addresses (CNAs) that have been assigned to each telephone device used at the customer sites;
each SSP of a customer site being adapted to receive a number of digits sent from a calling station;
means for identifying, at the SSP, the criteria necessary to trigger a query to the SCP;
means for formulating a Transaction Capabilities Application Part (TCAP) query message appropriate to the AIN trigger used;
means for transmitting a Signalling System 7 (SS7) message from the SSP to the SCP via a common transport facility;
means for pre-translating at the SCP the received message to determine a routing number to route the call to any one of said customer sites served with Centrex type services;
means for formulating a TCAP response message at the SCP containing the routing number;
means for transmitting the formulated message to the SSP of the customer site to instruct the telephone network how to complete the call;
and
means for translating the switch-supplied network node address (NNA) of the calling station to a CNA such that Centrex type terminating station features can be maintained at each customer site.

7 more elements

Dependencies are inferred from the claim text.

Virtual wide area centrex

Life of this patent

Virtual wide area centrex

Life of this patent

Abstract

Claims16