Note: Descriptions are shown in the official language in which they were submitted.
CA 02232772 1998-OS-25
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COMPLETING TELECOMMUNICATIONS CALLS IN A COMPETITIVE
LOCAL AND TOLL, ENVIRONMENT
Technical Field
This invention relates to methods and apparatus for providing
competitive, local and toll service in a national telecommunications network.
Problem
The U.S. telecommunications network is in a state of transition. During
the next several years, it is expected that the monopoly held by local
exchange
carriers will be substantially altered and that Competitive Access Providers
(CAPs)
will begin to offer customer access for toll calls to the already competitive
interexchange carriers, will provide local <:xchange service, or both. In
order to
accomplish this goal without creating an excessive burden on customers who
wish to
receive service from a CAP, it is expected that there will be a requirement
that a
change to a CAP need not be accompanied by a change of telephone number.
Further in the long run, it is expected that customers will be able to move to
another
geographic location within some reasonably defined region, and, in moving,
change
their local carrier, the switch from which they are being served, or both. The
ability
to change service providers without moving is called service provider number
portability; the ability to change location without changing a service
provider is
called geographic number or location portability. It is expected that in the
not too
distant future both will be required. In order to provide service in the face
of service
provider number portability and geographic number portability, the traditional
tie
between a customer's serving centxal office and the NPA-NXX portion of that
customer's telephone number will have to be broken and alternate arrangements
provided. Such alternate arrangements already exist for 700 service wherein
the last
seven digits of a 700 number bear no relation to the geographic location of
the
associated telephone customer. Other sen~ice access codes such as 500 are
being
planned for use with similar services. At the present time, this type of
facility is
limited to a small fraction of telephone customers. Accordingly, the problem
in the
prior art is that no sound economic arrangement has been proposed which offers
geographic number portability and service provider number portability to most
telephone customers.
CA 02232772 1998-OS-25
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Solution
The above problem is solved and an advance is made over the prior art
in accordance with our invention wherein each local exchange carrier is
provided
with access to a local universal database listing all numbers for a given
local region
served by a local exchange carrier and wherein each interexchange carrier is
provided with access to a national database listing all numbers for the
nation.
(Clearly, both of these databases can be implemented incrementally during a
period
of transition wherein for example, the national database need only store data
for
regions which have implemented service provider number portability andlor
geographic number portability and within these regions only for office codes
which
have diversity in the location and/or the lcxal exchange carrier of their
subscribers.)
For local calls, the local database is accessed to determine the identity of
the
terminating local exchange carrier and thc; terminating switch of the called
customer
while the national database is accessed to obtain similar information for toll
calls.
Advantageously, with this arrangement, the originating switch or a switch of
an
interexchange carrier can determine the identity of the local carrier serving
the called
customer and the switch from which that called customer is served.
In accordance with one feature of the invention, an alternate terminating
carrier and terminating switch can be identified for customers who require
especially
reliable service so that if the preferred carrier and switch are inaccessible,
the
terminating customer may be reached by ;an alternate route. In accordance with
another aspect of the invention, call detail. records for individual calls
include the
identity of the terminating exchange carrier and switch for toll calls. The
originating
local carrier and switch must also be identified if the interexchange carrier
is to
produce the billing record for a call, in order to rate calls properly with
geographic.
andlor service provider portability.
For local carrier switches for local or toll calls, the identity of the
originating local exchange carrier and switch, or the interexchange carrier,
respectively, can be optionally recorded in order to allow a single billing
center to
process calls from a plurality of carriers without requiring that the records
of each
carrier and switch be segregated. In order to route calls in a network which
has local
number portability, it is necessary to have a location routing number for
routing calls
to the particular switch which serves the called customer. Such a location
routing
number is used to identify that switch so that the call may be routed there.
In
accordance with one feature of applicants' invention, this location routing
number
(LRN) composes an area code and office <:ode (NPA-NXX) wherein each switch of
CA 02232772 2004-02-10
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the network has a unique LRN. If a switch serves customers having several
different
office codes, perhaps even office codes and having different NPA codes, such a
switch is identified by a single NPA-NXX code. While it may be convenient to
assign an NPA-NXX code that is used by at least some of the customers served
by
switch, it is not necessary; because each switch must have a distinct location
routing
number, it may not be possible, in some cases, for some of the switches,
especially
smaller switches of competitive access providers. However, if the switch is
identified
by an NPA-NXX code of some of the telephones that it serves, routing
translations
can remain the same for those telephones. Advantageously, the use of an NPA-
NXX
code as a location routing number provides a high degree of compatibility with
existing methods of routing telephone calls.
Summary of the Invention
In accordance with one aspect of the present invention there is provided a
method of establishing a telecommunications call from a caller, comprising the
steps
of: receiving a Dialed Number of a called party at a first switch of a first
local
carrier; determining whether said Dialed Number is for a toll-call connection
or a
local-call connection; if it is determined that said Dialed Number is for said
local-call
connection, accessing by said first local carrier a local database that
associates a
dialed number with an identity of a preferred local exchange carrier and an
alternate
local exchange carrier of said called party and of a preferred switch and an
alternate
switch for connecting said telecommunications call to said called party
specified by
said Dialed Number; and routing said telecommunications call to said preferred
carrier and to said preferred switch for connecting said telecommunications
call to
said called party specified by said Dialed Number, and routing said call to
said
alternate carrier and to said alternate switch for connecting said
telecommunications
call to said called party when said preferred carrier or said preferred switch
are not
available.
In accordance with another aspect of the present invention there is provided
in
a telecommunication network, a method of establishing a telecommunications
call,
comprising the steps of receiving a Dialed Number at a first switch of a first
local
carrier; determining whether said Dialed Number is for a toll-call; if it is
determined
that said Dialed Number is for a toll-call, accessing a national database that
links a
CA 02232772 2004-02-10
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telephone number with an identity of a preferred and alternate terminating
local
carrier and of a preferred and alternate switch for connecting said call to an
ultimate
called party specified by said Dialed Number; and routing said call to said
preferred
or said alternate terminating local carrier and said preferred or said
alternate switch.
Brief Description of the Drawings
FIG. 1 is an overall block diagram illustrating the operation of applicant's
invention;
FIG. 2 is a block diagram illustrating the arrangement for updating national
and local databases;
FIGS. 3-6 are flow diagrams illustrating the operation of applicant's
invention;
FIGS. 7 and 8 are diagrams illustrating the establishment of toll and local
calls
in accordance with applicant's invention; and
FIG. 9 illustrates the use of data for identifying a location reference number
for routing calls.
Detailed Description
FIG. 1 is a block diagram showing the relationship between telephone
customers, local service providers (i.e., local exchange carriers) and
interexchange
carriers. Individual customers 1-5 serve to originate or terminate telephone
traffic.
Some of these customers, such as customers 1 and 4, are connected to two
carriers in
order to provide especially reliable service. Local exchange carriers 6-10 are
connected to the customers and are connected to interexchange carriers 11-13.
Each
local exchange carrier includes one or more switches 17, a local universal
database
(LUDB) 18 and a billing recording system 19. Alternatively, a local universal
database can be shared by several or all local carriers. The switches are for
establishing telephone connections in the conventional way and are
interconnected by
the links shown in FIG. 1. The database 18 need only contain data for the
telephone
numbers of the region served by the local exchange carrier. Each of the local
exchange carriers serving a particular region stores in its database data
CA 02232772 1998-OS-25
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concerning all the numbers of the region so that in a broad sense, each of the
databases contain the same data. The database for a particular region and a
particular carrier is accessed through data links from each of the switches of
the
earner serving that region. While FIG. 1 shows individual databases for each
local
exchange carrier, these databases could be shared among a plurality of such
local
exchange earners; this is particularly straightforward since the databases are
accessed using data links.
The local exchange carriers are connected to interexchange carriers 11,
12, ..., 13, each of which contains one or more switches 14, and access to a
national
universal database (NUDB) 15 and a billing record system 16. The remarks made
previously about the local database are also applied to the national database
which,
of course, is very much larger. This national database can be concentrated or
distributed and can be shared among a plurality of interexchange carriers
since it is
accessed by data links from the switches that use the data of the database.
FIG. 2 shows an arrangement for updating the local and national
databases. A centralized service management system 201 transmits update
messages
to individual carrier local number portability service management systems 202
which transmit update messages to the local databases 203 of each of the
carriers 204. Similarly, the centralized sexvice management system 201
transmits
data messages to interexchange carrier local number portability service
management
systems 210, each of which are used to update the national databases 211 of
each of
the carriers 212.
Local access providers must provide update information to the
centralized service management system 201. The customer's new local service
provider is responsible for the update for the case in which the customer
changes
service providers. When a customer switches carriers, the original local
carrier may
be required to forward calls for a short period (a few days) until the
database has
been updated.
FIG. 3 is a flowchart of the routing procedure for this kind of
arrangement. The local exchange carrier switch receives the call (action block
301).
The local carrier switch makes a translation whether this is a local or a toll
call
(test 303). If geographic number (location) portability has been implemented
in the
region where the call is received, then in order to successfully complete test
303, the
local database will return the preferred terl~ninating local exchange carrier
and the
switch from which the terminating customer is served and this can be used in
conjunction with the identification of the originating switch to determine
whether
CA 02232772 1998-OS-25
this is a local or toll call. A call will also be a toll call if it is
recognized that the
local database will not contain data for that terminating customer. This can
be
determined, for example, from the NPA code of the terminating customer, or if
geographic number (location) portability has not been implemented from the
office
code of the called number. If as a result of test 303 it is determined that
this is a toll
call, then the call is routed to the pre-subscribed interexchange carrier or
if the
customer specifies an interexchange carrier by dialing an appropriate code,
then to
the specified dialed interexchange carrier I;see action block 305). The
interexchange
carrier receives the Automatic Number Identification (ANI) of the calling
customer,
and the Dialed Number (action block 307). The interexchange carrier then
accesses
the national database to determine the temninating carrier (and alternate
where
provided) and the terminating switch (and alternate where specified) (action
block 309). The interexchange carrier them routes the call to an egress switch
serving the preferred terminating carrier and transmits the terminating
carrier and
local office identification (action block 311). Test 313 determines whether
the
preferred carrier is available; if so, the call is completed to the called
customer via
that terminating carrier (action block 315). If the preferred carrier is not
available
(negative result of test 313), then test 317 determines whether an alternate
carrier has
been specified. If so, then test 319 determines whether the alternate carrier
is
available. If so, the call is routed to the alternate carrier for completion
to the called
customer (action block 321). If the alternate earner is unavailable, then the
call is
blocked and given blocked call treatment (action block 323). Similarly, if no
alternate carrier had been specified (negative result of test 317) then the
call is also
blocked (action block 323).
If the result of test 303 for determining whether this is a local or toll call
is that the call is a local call, then action block 401 (FIG. 4) is entered.
In action
block 401 the local exchange carrier switch queries the local database to
determine
the preferred carrier and switch (and alternate carrier and switch if so
specified).
Test 403 is used to determine whether the preferred carrier is available. If
so, then
the call is routed to the preferred carrier, a~ld the terminating carrier and
end office
identification are transmitted toward the terminating carrier (action block
405). If
not, test 407 determines whether an alternate carrier has been specified. If
so,
test 409 determines whether the alternate carrier is available. If so, then
the call is
routed to the alternate carrier for completion to the called customer. If the
alternate
carrier is not available (negative result of test 409) or if no alternate
carrier had been
specified (negative result of test 407) then the call is given blocked call
treatment
CA 02232772 1998-OS-25
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(action block 413).
FIG. 5 is a flow diagram showing the actions performed for billing a toll
call. The interexchange carrier receives the ANI and Dialed Number (action
block 501). The interexchange carrier translates the incoming trunk
identification to
identify the originating carrier (action block 503). Alternatively, signaling
information from the originating carrier can identify that carrier. The
interexchange
carrier then queries the national database to identify the terminating carrier
and
switch for the called number (action block SOS) and the interexchange carrier
prepares a call detail record including the ANI, Dialed Number, originating
and
terminating local Garner identification and switch identification, the
interexchange
Garner identity (in case billing records are processed for several carriers by
a single
processor), and elapsed time for the call (action block 507).
FIG. 6 is the billing procedure for local calls. The local Garner receives
the Dialed Number and the ANI of the originating customer (action block 601).
The
local Garner then queries the local database to identify the terminating
carrier and
switch based on the Dialed Number (action block 603). The local carrier then
prepares a call detail record including the ANI, Dialed Number, the
terminating
carrier and terminating switch identification.
For the case that the alternate terminating carrier is used, the alternate
terminating carrier and switch are substituted for the preferred carrier and
switch in
the call detail record.
FIG. 7 illustrates a toll call and illustrates some of the ways in which the
arrangement described herein has flexibility. A customer 701 has access to
three
different local carriers: namely, Local Exchange Carrier 711, Competitive
Access
Provider 713 and Cable TV provider 715. Assume that this customer elects for a
particular call to use the Competitive Access Provider 713. When the toll call
arrives at the ingress switch 731 of the selected interexchange carrier, the
call is
routed to the egress switch of interexchan,ge carrier 733, either the ingress
switch or
the egress switch may query a national universal database 741 to obtain
information
as to the carrier and office serving the called customer. The interexchange
carrier
switch querying database 741 supplies the called party number (NPA--NXX--
XXXX) and receives in response the identity or identities of the carriers) and
end
offices) of the local carrier serving the called customer. It is also possible
that the
database is queried from an intermediate switch of the selected interexchange
carrier;
this might happen, for example, if the call is of a special type handled by a
specialist
interexchange carrier switch. At any rate, the egress switch is informed,
either by
CA 02232772 1998-OS-25
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the querying switch, or directly by the database if the egress switch is the
querying
switch, of the identity of the preferred carl-ier(s) and the identity of the
end office for
each such carrier. The call is then routed, in this case via CATV carrier 725,
to the
terminating customer. Note that in the terminating region there is also a
Local
Exchange Carrier 721 and the Competitive Access Provider 723, so that there is
an
alternative for completing the call to the called customer 703. In order to
provide
revenue to the carrier that actually processed the call, the identity of the
originating
and terminating local carrier, as well as the interexchange earner, are
provided either
explicitly to the call detail records or implicitly because the record is made
by a
particular carrier.
FIG. 8 illustrates a local call and illustrates some of the ways in which
the arrangement described herein has flexibility. A customer 801 has access to
three
different local carriers, namely local exchange carrier 811, Competitive
Access
Provider 813 and Cable TV provider 815. Assume that this customer elects for a
particular call to use the Competitive Access Provider 813. When the local
call
arrives at a switch at Competitive Access Provider 813, the switch from the
Competitive Access Provider 813 accesses local universal database 841 with the
dialed number (NPA-NXX-XXXX) and receives in response the identity or
identities
of the carner(s) and end offices) of the local carrier serving the called
customer.
The Competitive Access Provider then routes the call via the preferred carrier
which
may be local exchange carrier 811 or Cable TV provider 815. Note that in the
particular case where illustrated in the dial,~ram wherein called customer 803
has
access to all three carriers, the call can be routed via a non-preferred
carrier if access
via the preferred terminating carrier is blocked. In order to provide revenue
to the
carrier that actually processed the call, the identity of the originating and
terminating
local earner are provided either explicitly to the call detail record or
implicitly
because the record is made by a particular carrier.
While in the preferred embodiment, the interexchange carrier accesses
the national database, the originating carrier can alternatively be arranged
to access
that database and forward the identity of the terminating carner(s) and
switches) to
the interexchange carrier.
For a local operator assistance call, the local carrier determines that the
call is a local operator call and sends the call to a local operator
assistance system
which may be part of the calling party's local carrier network, or in another
local
network (operator systems can serve multiple local networks). The originating
local
carrier is identified to the operator system either by incoming trunk
information or
CA 02232772 1998-OS-25
_g_
signaling. The operator system performs the requested operator service and
then
queries the LUDB to get the terminating carrier and terminating switch. It
routes the
call to the terminating carrier, passing the carrier and switch
identification. The
operator system makes a call detail record that includes both the originating
and
terminating, carrier and switch, identificarions.
For a toll operator call, the local Garner determines that the call is a toll
operator call and sends the call to the subscribed or dialed toll carrier
operator
system. The originating local carrier is identified to the toll operator
assistance
system either by incoming trunk.information or signaling. The operator system
performs the requested operator service and routes the call to a toll ingress
switch.
>From here, routing is the same as a toll call - the ingress toll switch
queries the
NUDB, etc. When the toll call is successfully routed, the terminating carrier
and
switch identifications are signaled in the backwards direction to the operator
system
to be included in the call detail record. Essential to the implementation of
Local
Number Portability (LNP) is the ability to associate a network destination
with a
ported dialed number. This information, identified as a Location Routing
Number or
LRN, will necessarily indicate the specific: switching entity which serves the
called
party and, therefore, to which the call must be routed. Clearly, the LRN will
be the
key element in the LNP database.
An LRN must be selected for each switching entity which terminates subscriber
lines. Although LNP, and in particular, the use of an LRN will significantly
impact
call processing in all networks, the format of the LRN can be selected to
minimize
the required network changes. Specifically, it would be desirable if the use
of the
LRN:
- allowed the continued use of cuwent network routing methods
- permitted the use of existing signaling protocols
- avoided the need for new technical standards
Any number of formats might be considered for use as an LRN. For example, a
simple S digit numeric code would allow the unique identity of up to 100,000
end
offices. Alternatively, the code could be designed to include routing
information
indicating, for example, a region of the country in which the end office was
located;
or the code could be designed to include the identity of the local service
provider.
All of these suggestions, however, fail to ~,atisfy the most important of the
above
mentioned criteria -- the need to retain the current routing algorithms in all
network
CA 02232772 1998-OS-25
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switches. Today, routing is based upon the geographic information contained in
North American Numbering Plan (NANP) numbers -- specifically the first six
digits
of those numbers or NPA-NXX. Accordingly, the use of an LRN in a format other
than NPA-NXX would create the need to develop routing based upon the new code.
It appears appropriate, therefore, that the L.RN retain the format of the
numbering
plan used to identify end offices today; that is, NPA-NXX.
In accordance with applicants' teachings, a. unique LRN, in the form of NPA-
NXX,
is assigned to each switching entity which terminates subscriber lines. The
LRNs
are assigned by a code administrator, likely the same administrator
responsible for
local number administration. Existing end offices which are presently
associated
with one or more NPA-NXXs, would select one of the NPA-NXXs currently
assigned to the office as the LRN. Local service providers establishing new
switching entities would, naturally, request and receive an LRN from the
administrator. An LRN need not contain tile NPA-NXX code of any customer
served by the switch identified by the LRN.
To avoid routing complexities it is important that an LRN assigned to any end
office
not be an NPA-NXX assigned to any other end office. For example, consider a
large
end office which currently uses four NPA-NXXs to identify customers served
from
that office. One of the four NPA-NXXs would be selected as the LRN for that
office.
The LRN for any other end office should not be selected from any of the three
(non-
LRN) codes assigned to the existing end office. This constraint eliminates the
need
to establish separate routing tables -- or domains -- to distinguish routing
based upon
LRNs -- for those dialed numbers that have been ported -- from routing based
on the
dialed number for those numbers that have not been ported. Rather, routing
tables as
they exist today, would be used to effect call completion. Finally, it is
assumed that
information associated with LRNs, such as service provider name, conunon
location
language identifier (CLLn code, tandem routes, vertical and horizontal
graphics
coordinates, etc., would be added to the Local Exchange Routing Guide (LERG).
Equally important in the selection and use of an LRN is its compatibility with
the
existing signaling methods used to transmit the necessary address information
required for proper call completion. Signaling messages are necessary to
provide
this inforniation either directly to the terminating switch or to an
intermediate or
tandem office. It will be necessary to carry both the LRN as well as the
dialed
CA 02232772 1998-OS-25
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number (DN) along the signaling path. The LRN is clearly required for call
routing
and the DN is needed by the serving end office to effect the connection to the
loop
assigned to the called party. The following describes the methodology through
which existing signaling methods can be used to forward this information.
Typically, signaling information is carried over a dedicated, common channel
signaling network using the SS7 protocol. Call set-up is effected using an
initial
address message (IAM) which contains several parameters, each containing
specific
infolnation related to the call. This signaling method is used to provide call
completion in a number portable environrr~ent by simply modifying the use of
existing parameters. Although the modification of the use of these parameters
requires industry agreement, it should not involve the more complex and time
consuming exercise of establishing and implementing the use of an entirely new
signaling parameter within the SS7 message.
Specifically, the SS7 IAM parameters that are involved are the called party
number
(CdPN) parameter and the Generic Address Parameter (GAP). Today, for non-
featured calls the CdPN parameter is populated with the DN and call routing is
performed using this number. (A non-featured call is one who dialed directory
number is used for routing the call, in contrast, for example, to 800 calls
wherein the
dialed number cannot be used directly for routing.) The GAP is an optional
parameter designated to transport a "user provided number" and is currently
used in
only a few instances. It is proposed that when a ported call is processed and
an LRN
is received as a response from an LNP database, the LRN is populated in the
CdPN
parameter of the IAM. It is further proposed that the DN be transmitted in the
GAP.
The contents of the CdPN parameter (the LRN) will be used as necessary to
route the
call. Because the information is in the NPA-NXX format, routing should proceed
without change. At the terminating end office the 6 digit format of the LRN
can be
identified by the switch to indicate a call for completion to a ported number.
With
that identification, the switch can be instructed to locate the number
originally dialed
-- and necessary to identify the called party -- in the GAP.
FIG. 9 illustrates the operation of applicant's invention with respect to the
use of a
location routing number. Telephones 901, 902, and 903 are connected to end
offices 911, 912, and 913, respectively. End offices 911, and 912 are in the
same
local region, whereas, end office 913 is connected to end offices 911, and 912
via
CA 02232772 1998-OS-25
-11-
trunks interconnecting interexchange carrier offices 920 and 921. Access
tandems 915 and 916 are used for accessing the interexchange carrier and for
interconnecting the end offices to databases as shown as local universal
database 951
and a national universal database 952. For each end office, a set of office
codes
served by that office is shown. The particular office code which is also used
as the
location routing number is shown in parentheses.
In the particular example shown, telephone station 415-887-1234 is connected
to end
office 912 having location routing number 415-267. End office 911 serves the
bulk
of the telephones having telephone numbers in the 415-887 office code. When
telephone 901 calls telephone 902 having telephone number 415-887-1234, a
check
is made in local universal database 951, table 930, and an entry 931 is found,
indicating that telephone 415-887-1234 is served by an end office identified
by
location routing number 415-267, i.e., end office 912. If no entry had been
found for
telephone 415-887-1234, then the call would have been routed using the 415-887
code to end office 911.
If telephone 901 calls telephone 903 having telephone number 201-334-9876,
such a
call is identified as being an inter-LATA (inter-local access transport area)
routed to
an interexchange earner which accesses a :national universal database in order
to find
the identity of the switch serving the terminating telephone. It is necessary
to
identify this switch in order to route via an exchange carrier that serves the
identified
switch. The national universal database 952 has an entry 942 in table 940 for
telephone number 201-334-9876 and that entry indicates that the location
routing
number of the terminating end office is 201-789. If no entry had been found,
then -
the 201-334 office code would have been used to route the call to end office
914
which serves the bulk of the 201-334 office code traffic.
Note that the databases need only store data for the numbers that are not
served by
the local switches serving the bulk of the numbers of a particular office
code. Data
need only be stored for the numbers of customers who have moved from such a
switch to another.
Consider the toll call associated with FIG. 9 in more detail.
1. An interLATA call is generated by an end user in California to a called
party in New Jersey. The dialed number is. (201)334-9876.
CA 02232772 1998-OS-25
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2. The call is recognized by the originating end office as an interLATA call
and the call is forwarded to the presubscribed interexchange carrier (IC).
3. Although the IC could test to identify the DN at either the originating or
terminating switch in its network assume the identification is performed at
the
originating IC switch. Specifically, the first 6 digits (201-334) of the DN
are
analyzed and identified as a potentially ported number.
4. Database query is launched to the appropriate NUDB database with the
DN (201) 334-9876.
5. Because the number has been ported, the response from the NUDB
database includes the LRN (201-789).
6. The call is routed based upon the LRN and the originating IC switch
formulates an SS7 IAM (initial address message).
7. The CdPN parameter is populated with the LRN (201-789) and the DN
(201) 334-9876 is inserted in the GAP.
8. The terminating IC switch routes the call based upon the LRN and
generates a signaling message to the designated end office.
9. If the terminating end office is SS7 and "LNP capable" (LNP=Local
Number Portability) (i.e. capable of recognizing the modified signaling
message):
- End office checks contents of CdPN parameter, recognizes the 6 digit
format and identifies the call as an "LNP" call.
- End office uses the information in the GAP (the DN) to route the call to
the appropriate subscriber loop.
10. If the terminating end office is not LNP capable, the
(n-1)st switch (i.e., the switch transmitting the signaling message) must
format the
signaling message so that the DN is contained in the CdPN parameter.
11. Similarly, if the EO is not SS7 compatible, the DN will be forwarded
using in-band (MF) signaling.
12. If the dialed number has not been ported, the call is routed and signaling
generated in the normal manner.
- The dialed number is populated in the CdPN parameter
- The GAP is not used
- The call is routed based upon the DN contained in the CdPN parameter.
In some cases, an end office switch may serve more than one carrier,
with different sets of customers, associated with different sets, telephone
numbers,
being served by different carriers. Under these circumstances, different trunk
groups
are likely to be used for the calls of the different carriers. The routing
arrangement
CA 02232772 1998-OS-25
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must be capable of selecting these carriers. Therefore, it is necessary to
have the
translations in the LUDB951 and NUBD 952 augmented with the identities of the
trunk groups or a routing index for finding such trunk groups. As shown in
FIG. 5,
such carriers must be identified for routing and entered in billing records.
It is to be understood that the above description is only of one preferred
embodiment of the invention. Numerous other arrangements may be devised by one
skilled in the art without departing from the scope of the invention. The
invention is
thus limited only as defined in the accompanying claims.
