Public switched telephone network access to public data network

A system and method for providing Feature Group B or Feature Group D access to the public data network for effecting point of sale transactions such as credit card authorization. The credit card authorization device includes a modem and auto-dialing mechanism which is connected by a station line to an originating central office switch. The originating central office switch is connected via Feature Group B or Feature Group D trunks to a designated destination central office including a stored program control (SPC) switch. The destination central office is a functioning central office connected to other central offices by non-Feature Group trunks. The Feature Group trunks are connected by the switch in the destination central office to a designated line which is connected to a line side modem which is connected via the public data network to a host computer for effecting the credit card authorization. The SPC switch at the destination central office converts the Feature Group number on the Feature Group trunk to a line side number for the station containing the line side modem. Common channel signaling and quick start or ground start are preferably utilized to optimize speed.

TECHNICAL FIELD 
This invention relates generally to the use of the public switched 
telephone network for the transmission of data and more particularly to 
using the public switched telephone network to access the public data 
network. 
BACKGROUND ART 
The evolution of the handling of credit card authorization transactions 
over the public switched telephone network is described in some detail in 
U.S. Pat. No. 4,796,292 issued Jan. 3, 1989, to Jerry S. Thomas and 
assigned to American Express Company of N.Y. A familiarity with the 
evolution of the public switched telephone network in the United States at 
the present date is helpful to an understanding of the present invention. 
The following background description summarizes portions of that 
discussion in conjunction with FIGS. 1, 2 and 3 which appeared in said 
U.S. Pat. No. 4,796,292. 
The public switched telephone network (PSTN) as it existed before the Bell 
System break-up, is shown in grossly simplified form in FIG. 1. Each 
central office 10 provided service over telephone lines 14 to telephone 
stations 12. Central offices were connected to each other by trunks 16. 
Trunks are distinguished from telephone lines by the use of heavy lines. 
Each central office included a switch 8 for effecting connections between 
lines and lines, and lines and trunks. (Other switching facilities 
including tandem switches were provided for effecting trunk-trunk 
interconnections.) In general, a trunk is a 5 communication path in a 
network which connects two switching systems and tandem switches switch 
trunk to trunk. A trunk circuit, associated with the connection of a trunk 
to a switching system, serves to convert between the signal formats used 
internally in the switching system and those used in the transmission 
circuit, and it performs logic and sometimes memory functions associated 
with supervision. A line, on the other hand, is a pair of wires carrying 
direct current and analog communication signals between a central office 
and a customer's terminal; a line-side connection is a connection of 
central of f ice equipment to a line. 
As the PSTN grew numerous interfaces and protocols developed and became 
standard. An interface is a shared boundary defined by common physical 
interconnection characteristics, signal characteristics, and meanings of 
interchanged signals. In telephony, the term "signaling" means the 
transmission of information to establish, monitor, or release connections 
and provide network control. Lines interfaced to central offices in ways 
which were distinct from those in which trunks interfaced to central 
offices. The physical connections were different, and even the number of 
wires could be different. The signalings were different. A protocol 
consists of procedures for communication between a sender and a receiver, 
of supervisory and address information, in order to establish and maintain 
a communications path. It is an agreed-to set of procedures so that 
communications between two ends will be intelligible in both directions 
(transmit and receive). 
As time passed and AT&T faced competition from other common carriers 
(OCCs), the PSTN developed as shown, once again grossly simplified, in 
FIG. 2. Bell System central offices were still connected by trunks 16 to 
other central of f ices. An OCC such as MCI or Sprint would provide 
switches 18 which could be accessed from central office lines. The OCC 
switches would be interconnected via their own network trunks 24. In order 
to gain access to a common carrier other than AT&T, a telephone subscriber 
would be connected over a telephone line to his central office, through 
his central office and perhaps others, and finally over another telephone 
line associated with the OCC. 
The quality of communications was generally not as good when going through 
the facilities of an OCC. This was the case even though the trunks 
actually used by the OCCs were leased from AT&T. The reason was related to 
the fact that poor performance is attributable most often to the inferior 
transmission performance on line-side connections. A typical AT&T Bell 
System call involved two lines 14, one at each end of the overall 
communication path; all other interfaces along the way involved trunk 
connections. An OCC, on the other hand, had an additional two line 
interface, as shown by numerals 20 and 22 in FIG. 2. Because each central 
office was connected over lines, not trunks, to an OCC switch, there were 
four line segments in each call, not just two. 
In order that the common carriers other than AT&T be able to provide the 
same superior service following break-up of the Bell System, and in order 
that equal access to the local exchange users be given to all long 
distance Interstate Carriers, several access arrangements were made 
available. These access arrangements are known as Switched Access 
Services. The term Interexchange Customer or Carrier (IC) is used to 
denote any subscriber of Switched Access Services, including an 
Interexchange Carrier. 
The geographic areas served by the Bell Operating Companies have been 
divided into Local Access and Transport Areas (LATAs). A typical LATA is 
shown in FIG. 3. A LATA is an area within which a Bell Operating 
Company--an Exchange Carrier (EC) or Local Exchange Carrier (LEC)--may 
offer telecommunication services. Interchange carriers (ICs) provide 
services between LATAS. The Interexchange Carriers are, AT&T, MCI, Sprint 
and others. The specific switched access arrangements offered by the Bell 
Operating Companies are known as the Feature Groups. An End Office (EO) is 
a Bell Operating Company switching system within a LATA where customer 
station loops (lines) are terminated for purposes of interconnection to 
each other and to trunks; a call may go directly from an End Office or be 
tandemed through a second office known as an Access Tandem (AT) to reach 
the IC. A tandem is a switching system in the message network that 
establishes trunk-to-trunk connections. As shown in FIG. 3, 
telecommunications within a LATA are handled by an EC, whereas 
telecommunications from one LATA to another are handled by an IC. 
An IC under the present scheme designates a location within a LATA for the 
connection of its facilities with those of the Bell Operating Company 
which serves that LATA. There are about two hundred LATAs in the United 
States, and each of the Bell Operating Companies serves all or portions of 
multiple LATAs. The location of interconnection designated by the IC is 
called a Point Of Presence (POP), and typically it is at a building that 
houses an IC's switching system or facility node. An IC may have more than 
one POP within a LATA. In FIG. 3 a POP is shown by the numeral 30. An 
aggregate of one or more IC trunks is shown by the numeral 32. Instead of 
the POP being connected to a single central office, what usually happens 
is that it is connected by trunks to an Access Tandem (AT). The AT, shown 
by the numeral 26 in FIG. 3, is in turn connected to multiple central 
offices by means of trunks. An Access Tandem is a Bell Operating Company 
switching system that provides a traffic concentration and distribution 
function for inter-LATA traffic originating/terminating within a LATA. The 
AT thus provides the IC with access to more than one End office within the 
LATA. (A central office is an End Office). 
For present purposes, what is important is that the LEC offers the IC a 
choice of four switched access arrangements called Feature Groups. Each 
IC, based on its own technical needs and business considerations, selects 
the access arrangement that it desires. The access arrangement involves a 
multiplicity of interfaces represented in FIG. 3 by the single trunk 28, 
it being understood that the drawing is only symbolic and there are in 
fact as many connections as there are maximum number of simultaneous calls 
that the IC expects to handle. 
Feature Group A is a two-wire line-side connection between the IC and the 
EC. Feature Group A is not of particular interest because it is a 
line-side connection and is the only one of the four access arrangements 
for which the calling party is billed any local tariffed charges, i.e., 
message units. The other three Feature Groups involve trunk-side 
connections. 
Feature Group B has an associated universal 7-digit (950-0/1XXX) access 
code and is used for the purpose of originating or terminating calls to or 
from subscribers. The XXX code is unique to each IC and, most importantly, 
it is the same throughout the country in all LATAs in which the IC has a 
presence. Feature Group B access arrangements include trunk signaling, 
trunk protocols, trunk transmission and trunk testing, and they provide 
answer and disconnect supervision. There can be two-wire and four-wire 
trunk terminating equipment, and, in general, there are supplemental 
features (as there are in the other Feature Groups) which are offered that 
allow an IC to specify substitutions for, or additions to, the standard 
arrangements as defined by the appropriate tariff. 
Feature Group C exists now but is transitional. AT&T, whose trunk-side 
connections are presently Feature Group C, will convert to Feature Group D 
as it becomes available. Feature Group B involves 2-stage dialing, the 
kind of arrangement which existed before subscribers could select an IC 
other than AT&T. With an arrangement such as that shown in FIG. 2, a first 
number is dialed in order to gain access to a line which is connected to 
the OCC facility, after a connection is established, a second series of 
numbers are dialed to tell the OCC the personal identification number of 
the caller (PIN) and the destination of the call. As an option, when the 
connection is established, Automatic Number Identification (ANI) 
information may be forwarded to the OCC. Feature Group D, on the other 
hand, provides true "Equal Access" in that a customer can presubscribe to 
the long-distance carrier of his choice. By dialing the digit 1, his call 
will be connected to a Feature Group D trunk at the selected ICs Point Of 
Presence. There is only one number dialed, that of the destination. While 
the invention is applicable to Feature Group D service, the illustrative 
embodiment of the invention is described in terms of Feature Group B 
service. 
Once a caller gains access to an ICs facilities, any subsequent dialing 
procedures are as specified by the IC for Feature Group A and Feature 
Group B service. Industry standards exist for the dialing plans for 
Feature Groups C and D. In-band tone dialing is usually employed, but in 
any event the EC is transparent to address signaling and data 
communications between the subscriber and the IC. As far as the interface 
between the EC and the IC is concerned, the IC can specify the type of 
supervisory signaling and interface to be used between the Bell Operating 
Company access facilities and the IC facilities at the ICs point of 
presence. The signaling options and interfaces that are available vary 
with the particular feature Group and tariff. 
A prior art credit card authorization scheme is shown in FIG. 4. A credit 
card authorization terminal 30 is connected via an ordinary telephone line 
34 to a central office 10. The authorization terminal includes a standard 
modem 32. At the beginning of the authorization process, the terminal 
dials a number which is associated with a line connected to a particular 
Value Added Network (VAN). The connection is established through central 
office 10. In the VAN 40, line 36 is connected to modem 38. Using the Visa 
protocol, the two modems communicate with each other. Modem 38 is 
connected via a digital interface to a Packet Assembler/Disassembler (PAD) 
42 or some other multiplexer or concentrator within the VAN. The PAD 
establishes communication with a host over leased line 44 or some other 
communication channel. 
As described above, the service establishment pays for a local call to the 
VAN. The VAN charges the credit card company for handling the call. There 
is no way to reduce the charges paid by the service establishment because 
a local call through the central office is being placed. It is also 
apparent that depending upon the location of the VAN in a particular city, 
the authorization terminals must have different numbers preprogrammed in 
their automatic dialers. 
What is shown in FIG. 5 is a way that a service establishment can be 
relieved of paying for a local call. Also, the scheme of FIG. 5 must be 
employed when there is no VAN presence near the credit card authorization 
terminal. In this case the terminal establishes a call through the dial 
network 46, and over line 34 and trunk 48 to an AT&T facility 50. The AT&T 
lines are extended as an 800 call to modems in VAN 40. In this case the 
service establishment does not pay for the call; AT&T pays the Bell 
Operating Company. The credit card company picks up all charges of AT&T 
and the VAN. The arrangement of FIG. 5 is not preferred because of the 
cost of an 800 call. 
The arrangement of FIG. 6 is not known to exist or to have existed but has 
been hypothecated in the said U.S. Pat. No. 4,796,292 as a kind of system 
which might be devised by a "telephone man". Lines 14 are connected to 
authorization terminals and are within the LATA of the Exchange Carrier. 
Some of the EC trunks, Feature Group B or D, are extended to the Point of 
Presence of an IC. A switch 54 is provided for extending trunks 28 to 
their destinations, in this case lines connected to modems and a PAD. 
Communications originate in the terminal, and a terminating modem in the 
POP is required to communicate with the modem in the terminal. Modems 
interface with lines, not trunks. A switch is the standard mechanism for 
interconnecting lines and trunks. Since only trunks come into the POP, a 
switch is necessary to connect an incoming trunk to a modem line (just as 
the switch of a central office connects a trunk and a subscriber line). 
This approach allows a terminal to be connected to the host. The service 
establishment need not be billed for the call because with Feature Group B 
or D service, the IC pays the EC for each call which is placed. The IC is 
the only source of billing to the calling party, and with switching 
equipment having sufficient intelligence, it would be possible for the IC 
to bill the credit card company for calls placed to its host installation. 
This FIG. 6 arrangement is stated to be not feasible, however, because of 
the cost of switch 54. A typical modem is stated to cost in the order of 
$500. A switch for 100 lines is stated to cost in the order of $200,000. 
That would make the cost per modem not $500, but $2,500. That is stated to 
be impractical. And it is further stated there is no apparent way to avoid 
the use of the switch. There is a modem in each authorization terminal. 
There must be a modem at the other end of the connection. Modems have line 
connections. The EC/IC interface is over a Feature group B or D trunk. 
There is no way that a trunk can be interfaced with a conventional modem. 
Not only may the number of wires in the trunk be different from the number 
of wires at the modem input, but the signaling requirements are totally 
different. A costly switch is stated to be the device which allows a modem 
line to be connected to a trunk in the hypothecated solution of FIG. 6. 
In U.S. Pat. No. 4,796,292 there is proposed an arrangement for authorizing 
credit card transactions wherein the credit card company obtains a 3-digit 
Customer Identification Code (CIC) in the manner of an Interexchange 
Customer or Carrier. At its POP there are provided dedicated, modems and a 
PAD or: other multiplexer or concentrator which is connected to the host. 
However, the modems are not conventional modems but are specially designed 
to provide a trunk-side interface. In the illustrated embodiment in that 
patent, E & M signaling and T1 interfaces are used. These trunk-side 
interface modems are stated to be only slightly more expensive than 
conventional modems. The proffered advantage is a reduction of the cost 
associated with local telephone calls involved in the transaction. 
In the hardware embodiment of this proposal the Local Exchange Carrier 
(LEC) provides Feature Group B service on T1 access facilities using 
conventional E & M trunk protocol. The T1 link is connected to a 
conventional 24channel channel bank that includes a T1 trunk hardware 
interface. As stated the modem is designed to execute a trunk protocol so 
that at the two ends of the transmission path, namely the LEC and the 
modem, a trunk protocol is executed. In view of the fact that the modem is 
provided with a ground start interface the E & M channel bank cards must 
be modified to provide a ground start interface for the modem. An 
arrangement to effectuate this proposal is illustrated in FIG. 7 which 
comprises a combination of FIGS. 3 and 7B from U.S. Pat. No. No. 
4,796,292. The channel bank is connected to the Access Tandem where the 
LEC establishes a trunk connection. The Access Tandem exercises a trunk 
protocol. 
SUMMARY OF THE INVENTION 
According to the present invention it has been found that it is possible to 
provide an improved point of sale or credit card authorization service 
without the need for extra switching or specially designed modems. In that 
arrangement an existing LEC End Office is selected as the designated EO 
where the Feature Group B or Feature Group D trunk terminates. The point 
of sale device dials a Customer Identification Code (CIC) such as 
950-1/0XXX or 7/10 digit dialing address that provides access to the 
designated end office. According to this invention the software at that 
end of f ice then effects address digit manipulation and/or special digit 
interpretation to convert the incoming address to a unique local address 
on the line side. The EO switch has the ability to delete digits or prefix 
new digits that conform to the line number(s) where one or more 
conventional modems are connected. This feature is typically called code 
conversion and is an available feature in existing end office switches. 
The end office switch also can perform special digit interpretation and 
routing for dedicated trunk groups. A pool of modems may be located at the 
designated end office and connected to the line side of the switch by a 
line hunting group. The code converting process substitutes the telephone 
number of the line hunting group (NXX-XXXX) for the 950-1/0XXX CIC number 
that it received. The special digit interpretation process directs the 
call via a dedicated routing table that selects the unique end office line 
hunting group. The end office thus connects the incoming trunk to an 
available line circuit within the line hunt group wherein each line is 
equipped with a conventional modem. Each modem is directly connected to 
the Packet Data Network (PDN) and the modem and PDN respond to the signals 
and information generated by the point of sale terminal by passing the 
call information to or from the host computer. When the host and the point 
of sale terminal are finished exchanging information, both ends disconnect 
and all connections are restored to the idle state. It is a feature of the 
invention that the end office is preferably established in a Common 
Channel Signaling (CCS) environment ordinarily using Signaling System 7 
(SS7). This permits faster connection to the designated end office. 
Instantaneous signaling to activate the modem is applied at the line in 
the form of immediate ringing or ground start. 
It is accordingly an object of the present invention to provide an improved 
point of sale credit card authorization service which utilizes currently 
available equipment so as to provide fast, efficient and effective service 
in a economical manner. 
It is another object of the invention to provide an improved point of sale 
terminal device service within the context of the existing Public Switched 
Telephone Network without requiring specially designed equipment for 
interfacing with the Packet Data Network (PDN). 
It is another object of the invention to provide an improved business point 
of sale terminal device service within the context of the existing public 
switched telephone network using an existing end office and its switch as 
the designated end of f ice where the Stored Program Control (SPC) switch 
is arranged to effect a code converting process or special digit 
interpretation process to convert an incoming CIC dialed by the point of 
sale terminal device to a line side address for conventional modems 
connecting to the Packet Data Network and host computer. 
It is another object of the invention to provide an improved business point 
of sale terminal device service in the context of the current public 
switched telephone network using common channel signaling and immediate 
ringing features to optimize the speed of operation. 
It is another object of the invention to provide an improved business point 
of sale terminal device within the context of the existing public switched 
telephone network using available Feature Group B or Feature Group D 
technology while obviating any requirement for modem equipment having a 
trunk side interface.

BEST MODE FOR CARRYING OUT THE INVENTION 
In current telecommunications and data networks "In Channel" Signaling is 
being replaced with Common Channel Signaling (CCS) in which control 
signals are carried over paths completely independent of the voice 
channels. The common channel can be configured with the bandwidth required 
to carry control signals for a large variety of functions. Thus both the 
signaling protocol and the network architectures to support that protocol 
are more complex than "In Channel" signaling. 
CCS provides a method for exchanging information between Stored Program 
Control Systems (SPCS) that are inter-connected through a network of 
signaling links. CCS network nodes may include but are not limited to 
switching systems, network databases and operator service systems. The 
current common protocol for CCS is Specification of Signaling System 7 
(SS7) which is described in the following Bellcore (Bell Communications 
Research) documents. (Section 6.5, LSSGR Issue 2, Jul. 1987, 
TR-TSY-000506, a module of TR-TSY-000064). 
Referring to FIG. 8 there is shown a simplified diagram of an SPC telephone 
network linking individual subscribers through Central offices (Cos) which 
are connected by trunks and linked by a typical CCS network. The COs 
typically consist of a programmable digital switch with CCS communications 
capabilities such as an AT&T 5ESS or Northern Telecom DS-100 or the like 
and may or may not be equipped and programmed to serve as Service 
Switching Points (SSPs). In FIG. 8 a series of central office switches 
10,, 12 and 14 are shown connected to groups of local subscribers 16, 18 
and 20 by conventional local loops or subscriber lines. The COs 10, 12 and 
14 are connected by trunk circuits 22 and 24, by way of example, and are 
also connected by one or more access tandems (not shown). Common Channel 
Signaling is provided by SS7 data links 26-36 extending between each CO 
and Signaling Transfer Points (STPS) 38 and 40. These local STPs may be 
connected to state or regional STPS, not shown. 
A pair of STPs is conventionally provided per LATA to provide redundancy so 
that in the event of failure of one the other immediately assumes its 
load. Similarly, if one STP becomes overloaded the other shares the load 
to create a load balance. The paired STPs are connected by Clinks so that 
each STP understands what the other is doing at all times. The STPs may be 
configured to continually share the load or may be configured in a hot and 
stand-by capacity. Generally speaking, one will basically monitor the 
other while they share the load. If one goes down the other is immediately 
aware of the situation via the C-link and picks up the load to avoid an 
outage. Thus each of the COs 10, 12 and 14 are connected to each of the 
STPs 38 and 40. The STPs provide call processing data transfer between the 
various COs in the normal manner of SS7 common channel signaling. 
Referring to FIG. 9 there is shown an arrangement of the public switched 
telephone network and public data network for carrying out the invention 
according to a preferred embodiment. In FIG. 9 there is seen a public 
switched telephone network as illustrated and described in connection with 
FIG. 7. Connected to an initiating or originating end office which is here 
illustrated by the central office 10, is a credit card authorization 
terminal 42 including the conventional modem 44 and auto-dialing device 
46. The credit card authorization terminal 42 is connected by a station 
line 48 to the central office 10 and receives dial tone from that office. 
Connected to a designated end office, which is here illustrated as central 
office 12, is a conventional line side modem or modem pool arrangement 50. 
The modem 50 exercises a line protocol and is connected to the central 
office 12 via a line hardware interface and line 52. The modem 50 may be 
conveniently located at or adjacent to the end office 12. Modem 50 is 
connected by an outgoing tie line 54 to a packet switch in the public data 
network, indicated generally at 56. Conventional X.25 packet protocol or 
other protocols may be used. The public data network 56 connects to a host 
computer 58 for effecting the credit card authorization in the 
conventional manner. 
The originating central office 10 is connected to the terminating central 
office or end office 12 via Feature Group B or Feature Group D trunks 
which are indicated diagrammatically at 60, although it will be understood 
that the Feature Group trunk(.s) may be included within the trunk 
connection 22 between the central offices 10 and 12. It will be 
appreciated that while the invention is illustrated in terms of 
originating central office 10 and terminating central office 12 there may 
be one or more central office(s) and/or tandem switch(es) between the 
originating central office and the terminating central office connected by 
Feature Group B or Feature Group D trunks executing conventional E & M 
trunk protocol. The originating and terminating central offices need not 
be in the same LATA. 
The Feature Group trunk 60 interfaces with the station line 52 at the 
central office switch 12 through a code conversion or special digit 
interpretation process. Code conversion is an option in most SPC switching 
systems used by LECS. The software translations in the switches have the 
capabilities to do address digital manipulation. The switch software 
converts the incoming address to a different address on the line side. The 
end office switch has the ability to delete digits and prefix new digits 
that conform to the line number(s) where the modems are connected. Special 
digit interpretation is also an option in most SPC switching systems used 
by LECS. In this case, the incoming digits are "translated" via a 
dedicated routing table which selects a unique end office line or line 
hunting group. The unique end office lines are where the modems are 
connected. 
When a bank of modems is used with a line hunt group the end office switch 
connects the incoming trunk to an available line circuit within the line 
hunt group assigned for the credit card authorization device. Each line is 
equipped with a modem. When ringing or quick start on the line begins, the 
modem is activated and aligns itself in the proper mode to receive signals 
from the credit card authorization device and convert them to the required 
digital format for forwarding to the public data network. 
At this point the call to the CIC or 950-1/0XXX number is completed. Each 
modem is directly connected to the Packet Data Network, Public Data 
Network (PDN) or other data communications or data processing equipment, 
and the modem and PDN will respond to the signals and information 
generated by the credit card authorization device by passing the call 
information to/from the host computer. When the host and the credit card 
terminal are finished with exchanging information, both ends disconnect 
and all connections are restored to the idle state. 
The operation of the system of the invention is as follows. A call is 
initiated from the credit card authorization terminal by the auto-dialing 
device dialing a CIC number or Feature Group access number such as 
950-1/0XXX. The call is routed over the public switched network to the 
designated end office 12 using SS7 network signaling over CCS lines 26 and 
28. While conventional signaling may be used CCS signaling permits a 
faster connection to the designated end office. 
The 950-1/0XXX call comes in on the incoming Feature Group B or Feature 
Group D trunk 60 to the designated end office 12 to terminate on the trunk 
side of the designated end office switch. The Feature Group B or Feature 
Group D trunk is connected by the stored program control (SPC) switch at 
the end office 12 to the station line 52 by code converting to a directory 
number or using special digit interpretation and routing for the line 52. 
If more than one line is required to handle the demand subsequent lines 
may be provided in a multiple line hunt group. This directs the call from 
the credit authorization device 42 to a line location, namely the modem or 
modem bank 50, which comprises a conventional line side modem or modem 
bank. Instantaneous signaling to alert the modem is applied at the line by 
quick start, ground start or immediate ringing. This signal is speeded by 
the use of CCS or SS7 signaling. The modem is connected via the line 54 
and public data network 56 to the host computer 58 for effecting the 
authentication. Once the connection is made to the host computer the 
exchange of information between the end user's or initiator's terminal 
device or credit card authorization device can begin. 
The method may be summarized as comprising the steps of: 
accessing the public switched telephone network from the credit card 
authorization device by the auto-dialing mechanism connected via a station 
line to an originating central office switch auto-dialing a CIC number; 
routing the call over the network using SS7 network signaling or 
conventional network signaling and connecting the originating central 
office via Feature Group B or Feature Group D trunks to a terminating 
central office switch in the telephone network; 
converting the CIC trunk call to a line side number at the terminating 
switch under control of the stored program of that switch and connecting 
via a station line to a conventional line side modem; 
transmitting an output from the line side modem over the public data 
network via packet switching to a host computer for effecting the credit 
card authorization. 
It is important to recognize that the end office switch functioning in the 
manner of the invention is a conventional end office switch which 
simultaneously functions to perform central office switching operations. 
No additional equipment is necessary and no special purpose switches or 
modems are required. 
While the specific application discussed in the preferred embodiment has 
been credit card authorization it will be appreciated that other point of 
sale terminals may be used. Thus a car rental agency having reservation 
booths in hotels may provide cards which actuate point of sale terminals 
to signal the rental car site so that the car is ready and waiting by the 
time that the customer reaches the site. Cards may also be provided for 
ordering products which may be encoded in the cards or designated by key 
pad actuation. 
It will be appreciated from the foregoing that the system of the invention 
provides an improved point of sale credit card authorization service which 
utilizes currently available equipment so as to provide fast, efficient 
and effective service in an economical manner. The service is provided 
within the context of the existing public switched telephone network and 
packet data network without requiring specially designed equipment for 
interfacing between such networks. Common channel signaling and immediate 
ringing features are preferably provided to optimize the speed of 
operation. Available Feature Group B or Feature Group D technology is 
utilized without any requirement for modem equipment having a trunk side 
interface. 
It will be readily seen by one of ordinary skill in the art that the 
present invention fulfills all of the objects set forth above. After 
reading the foregoing specification, one of ordinary skill will be able to 
effect various changes, substitutions of equivalents and various other 
aspects of the invention as broadly disclosed herein. It is therefore 
intended that the protection granted hereon be limited only by the 
definition contained in the appended claims and equivalents thereof.