Method and apparatus for processing a sequence of calls

A method and apparatus for processing a sequence of calls directed to different destination sites from a single calling site via a provider having a connection-based tariff structure that employs first and second levels of connections in order to increase cost efficiency. The first level connection is from the provider to an intermediate site, such as a server, with the first level connection being maintained throughout the sequence of calls. The second level connection is formed from the intermediate site to the destination sites in the sequential order determined by the calling party. Each call to a destination site includes a different second level connection that is terminated from a completion of the call, without affecting the first level connection. The call information relating to the different calls in the sequence is transmitted from the calling site to the intermediate site by techniques such as the transmission of DTMF signals or conventional digital call setup signals. In one embodiment, the provider is an exchange carrier of air-to-ground telecommunications capability.

BACKGROUND OF THE INVENTION 
The invention relates generally to communications servers and more 
particularly to methods and apparatus for processing a sequence of calls. 
DESCRIPTION OF THE RELATED ART 
There are a number of approaches available to communications service 
providers for charging users for access to equipment, such as trunk lines 
and switching circuitry. According to one approach, a communications 
service provider establishes a fixed monthly tariff. This is the approach 
adopted by many service providers of the global communications network 
typically referred to as the Internet. A subscriber of an Internet Service 
Provide (ISP) may be charged a monthly amount that does not vary with the 
access time required by the subscriber. 
Another approach is to establish a tariff table that is primarily based 
upon access time. This approach may be based purely upon time or may 
include consideration of other factors. For example, the tariff may be 
greater for access to a database of chemistry-related periodicals than for 
access to a database of telephone numbers. 
A communications service provider also may establish a hybrid of the fixed 
monthly tariff and the time-dependent tariff. For example, a local 
exchange carrier for routing telephone calls typically charges a 
subscriber a monthly fee for unlimited local toll-free calls, but the 
subscriber is charged for individual long distance calls. The tariff table 
for the long distance calls is dependent upon both distance and duration. 
In yet another approach, the charge to a subscriber is determined on a per 
connection basis. There is a fixed tariff that may be considered as a flat 
connection fee. This connection-based approach is best suited for 
communications applications in which the cost of maintaining connectivity 
between a calling party and a called party is substantially insignificant 
relative to the cost of establishing the connectivity. Alternatively, the 
approach may be selected by a service provider for its ability to simplify 
billing practices while charging users based upon the levels of use. 
Airphone carriers often utilize the connection-based tariff approach. An 
air-to-ground communications system may include a network of ground radio 
base stations connected to a single ground switching station. Calls 
directed from an airphone are routed from an aircraft to one of the base 
stations and then to the ground switching station. The ground switching 
station is connected to the public telephone switching network (PSTN), 
which routes the call to the called site. As an alternative, the 
transmission from the aircraft may be to a satellite which redirects the 
transmission to a satellite earth station for routing via the PSTN. In 
either case, establishing the connectivity is the major cost incurred by 
the carrier in completing the call. A significant portion of airphone 
calls are made from a grounded airplane. As an example of implementing a 
connection-based tariff structure, each call directed from an airphone or 
directed to an airphone may result in the airline passenger being charged 
$15, regardless of the length of the conversation. If the passenger places 
five separate calls, the total charge to the passenger will be $75. The 
tariff is charged even if the calls are all of short duration, as may be 
the case for downloading electronic mail and confirming afternoon 
appointments. Thus, the substantial cost of connectivity incurred by a 
carrier and passed on to the passenger may translate into an excessive 
tariff when calculated on a per minute rate. Similar circumstances may 
occur in other communications areas, such as a tariff structure of an ISP 
that utilizes the per connection approach. 
What is needed is a method and apparatus which reduce the likelihood of a 
communications provider charging an excessive amount for a sequence of 
calls as a result of implementing a per connection tariff structure. 
SUMMARY OF THE INVENTION 
A method and apparatus of processing a sequence of calls directed to 
different destination sites from a single calling site include providing a 
call server that functions as an intermediate site for first and second 
connection levels from the calling site to a destination site. 
Connectivity of the calling site to a destination site includes routing 
calls utilizing a provider that implements a tariff structure on a per 
connection basis. That is, a call tariff is charged for each connection 
established by the provider. The preferred embodiment of the method 
includes establishing a first level connection from the provider to the 
intermediate site of the server, with the caller thereby incurring the 
call tariff. Call information regarding the destination site of the first 
call in the sequence is then provided to the intermediate site via the 
first level connection. In response to receiving the call information, a 
second level connection is established between the intermediate site and 
the destination site of the first call in the sequence. Upon termination 
of the first call, the steps of receiving call information at the 
intermediate site and establishing a second level connection are repeated 
to provide connectivity between the calling site and a destination site of 
a second call in the sequence. The process is repeated for all of the 
calls of the sequence. Since the first level connection is maintained 
throughout the sequence, the provider is required to incur the cost of 
establishing connectivity only once. Consequently, there is a potential 
savings to the calling party, depending upon the tariff structure of the 
intermediate site. 
In the preferred embodiment, the steps of sequentially receiving the call 
information at the intermediate site and establishing the second level 
connections from the intermediate site to the different destination sites 
is implemented in a manner transparent to the provider. While not 
critical, the reception of the call information may be executed by 
detecting conventional call setup signals from the calling site, such as 
digital telecommunications signals or dual tone multifrequency (DTMF) 
signals. Establishing a second level connection may be a pass-through 
operation of the call setup signals to a public switched telephone network 
(PSTN) or may be a regeneration of at least some of the call setup signals 
at the intermediate site. In one embodiment, both the first and the second 
level connections utilize the PSTN. 
The provider may be an airphone carrier which charges an airline passenger 
a fixed tariff for each call that is placed via an airphone. 
Alternatively, the provider may be an Internet Service Provider (ISP) 
which charges on a per connection basis. The calls may be voice calls or 
may include multimedia signals. 
The intermediate site is preferably a call server having an interface 
connected to the PSTN. A first switching circuit establishes an off-hook 
state upon receiving an incoming call from the calling site via the 
provider, which may be an exchange carrier. A processor at the call server 
receives the call information in sequence while maintaining the off-hook 
state for the incoming call from the exchange carrier. In response to the 
received call information, outgoing calls to the destination sites are 
initiated and a second switching circuit connects the incoming call from 
the calling site to the outgoing calls to the destination sites.

DETAILED DESCRIPTION 
With reference to FIG. 1, in one embodiment, the method is used with a 
conventional air-to-ground communications system that includes a number of 
airphones 10, 12 and 14 connected to an interface 16. The airphones may be 
limited to voice communications, and/or may be capable of transmitting 
video, user data and other multimedia information. The airphones are 
located in the passenger area of an airplane, while the interface 16 is 
positioned on the plane to accommodate wireless transmissions to an 
exchange carrier 18. The interface includes a number of transceivers for 
transmitting and receiving radio frequency signals to and from a base 
station of the exchanger carrier 18. The number of transceivers determines 
the maximum number of calls that can be conducted simultaneously. For 
example, each transceiver may be dedicated to a single call, so that 
resource capacity of the interface is reached when there is a one-to-one 
correspondence between the number of transceivers and the number of calls 
being conducted. 
The equipment of the exchange carrier 18 is not critical to the invention. 
The equipment may include a number of ground stations connected to a 
single ground switching station which is coupled to a public switched 
telephone network (PSTN) 20. Alternatively or additionally, the exchange 
carrier 18 may include communications satellites which transmit and 
receive call information between the transceivers of the interface 16 and 
a ground switching station. 
A call initiated from the airphone 10 may be directly linked to a called 
destination site 22, 24 and 26 via the interface 16, the exchange carrier 
18, and the PSTN 20. This direct link is conventional in air-to-ground 
communications. The calling party is charged by the exchange carrier 18 
according to an established tariff structure. Often, the tariff structure 
for the air-to-ground communications system is connection based. That is, 
each call initiated or received by a caller results in the airline 
passenger being charged a flat fee, which will be designated herein as 
"x." For example, x=$15. A sequence of calls that includes one call to 
each of the destination sites 22, 24 and 26 results in the passenger being 
charged 3.times.. The value of x is partially determined by the cost of 
establishing connectivity between the interface 16 and the equipment of 
the exchange carrier 18 and the cost of establishing connectivity from the 
exchange carrier to the appropriate destination site via the PSTN 20. 
Consequently, reducing the number of required separate connections to and 
from the exchange carrier in order to complete a sequence of calls from a 
single calling site reduces the connectivity costs incurred by the 
exchange carrier. Moreover, when the method that will be described below 
is used as the means for reducing the number of required carrier 
connections to complete the call sequence, there may be a substantial 
savings to the calling party. 
According to the invention, the first connection from the equipment of the 
exchange carrier 18 is to an intermediate site 28, which may be referred 
to as a server. The server is "intermediate" in the sense that it is not a 
destination site for connection of a calling party to a called party, but 
is instead an additional site through which the calling information is 
channeled. FIG. 1 illustrates the preferred embodiment, in which the 
intermediate site is connected to the exchange carrier 18 via third party 
equipment, such as the PSTN 20. However, if the exchange carrier is to be 
the primary beneficiary of the server capability, the intermediate site 
may be located between the conventional equipment of the exchange carrier 
18 and the PSTN 20. 
When a passenger located at the airphone 10 intends to complete a sequence 
of calls to different destination sites 22, 24 and 26, the passenger may 
initiate a "preliminary" call to the server 28. This results in the 
passenger being charged x amount for the call, since the equipment of the 
exchange carrier 18 must establish connectivity between the carrier and 
the server. This first level connectivity between the carrier and the 
server is shown at step 30 of FIG. 2. The process for establishing the 
first level connectivity is identical to the conventional process of 
establishing direct connectivity from the exchange carrier to one of the 
destination sites. 
Call information relating to the first call in the sequence is then 
provided by the passenger at airphone 10 and is received at the server 28, 
as shown by step 32 in FIG. 2. In its simplest form, the call information 
is a telephone number of the desired destination site and is received at 
the server by means of dual tone multifrequency (DTMF) signals or 
conventional digital communications signals. The server utilizes the 
calling information to initiate a second level connectivity at step 34. 
The second level connectivity is from the server 28 to the destination 
site identified in the calling information. In FIG. 1, the first level 
connection is represented by communications lines 36 and 38, while the 
second level connection is identified by communications lines 40 and 42. 
Preferably, steps 32 and 34 of receiving the calling information and 
establishing the second level connectivity are executed in a manner 
transparent to the exchange carrier 18. Consequently, no additional 
expenses are incurred by the carrier. 
The step 34 of establishing the second level connectivity can be initiated 
at the server 28 by generating DTMF tones or digital signals that are 
utilized by the PSTN 20 to connect the appropriate destination site 22, 24 
and 26. Alternatively, DTMF or digital signals generated by the passenger 
at the airphone 10 may be passed through the server 28 to the PSTN. In 
this alternative embodiment, both the exchange carrier 18 and the server 
28 function as conduits for the DTMF or digital signals for initiating the 
first call of the sequence. 
Following completion of the first call in the sequence, the second level 
connectivity represented by communications lines 40 and 42 is terminated. 
This is shown at step 44 in FIG. 2. However, the first level connectivity 
is maintained. In decision step 46, the issue is whether another call to 
one of the destination sites 22, 24 and 26 is to be initiated still 
utilizing the first level connectivity. There are a number of available 
embodiments to execute this decision step. For example, the server 28 may 
transmit voice prompts to the caller at the airphone 10 via the first 
level connection. Thus, when the user signals termination of the first 
call to a destination site, a voice prompt from the server 28 may be 
triggered to request an indication of whether a second call is to be made 
by the passenger. In another embodiment, the passenger has prior knowledge 
of a termination-and-reinitiate signaling process that may use DTMF 
signals. For example, one key of a telephone keypad may be designated as 
the key to press to indicate termination of both of the first and second 
level connections, and a different key may be designated as the key to 
press to indicate that a subsequent call is to be made. In a third 
embodiment, the first level connection is terminated after passage of a 
timeout threshold, during which time a dial tone is provided by the call 
server (e.g., 30 seconds). The passenger then has the time threshold to 
initiate a subsequent call. A difficulty with this embodiment is that 
airphones are often shared by different passengers, so that there is a 
concern that a second passenger will initiate a call prior to passage of 
the timeout threshold of the first level connection established at step 30 
for a first passenger. Therefore, the voice prompt embodiment is 
considered to be the preferred embodiment. 
If at decision step 46 it is determined that the passenger wishes to 
initiate a second call to a destination site 22, 24 and 26, the call 
information is input by the passenger at airphone 10 and received at the 
server 28, as shown at step 48 in FIG. 2. Execution of step 48 may be 
identical to the execution of the step 32 of receiving the first calling 
information. For example, DTMF signals from the airphone are transmitted 
through the first level connection to the server which acts as a conduit 
for relaying the DTMF signals to the PSTN 20. Alternatively, the required 
DTMF signals may be generated at the server in response to receiving the 
calling information at step 48. The process flow then returns to step 34 
in order to establish a second level connectivity to the new destination 
site. 
With completion of the second call in the sequence of calls, the second 
level connection is terminated at step 44 and the process returns to the 
decision step 46. This loop is continued until the final call in the 
sequence is completed. At that time, the decision at step 46 will be that 
there is no further call to be initiated. Consequently, the first level 
connectivity is terminated at step 50. 
Exemplary components of server 28 of FIG. 1 are shown in FIG. 3. An 
interface 52 is connected to the PSTN 20 by means of communication lines. 
For example, the interface may include conventional line cards and the 
communication lines may be leased analog or digital trunk lines. A first 
switch 54 is an input device that establishes an off-hook state upon 
receiving an incoming call. The condition of the first switch 54 
determines whether the first level of connectivity to the exchange carrier 
18 of FIG. 1 is established. That is, when the first switch is in an 
off-hook state, connectivity between the server 28 and the exchange 
carrier 18 is provided via the communication lines 36 and 38 of FIG. 1. 
One output from the first switch is an input to a processor 56 that 
controls operations of the server 28. Another output of the first switch 
54 is an input to a second switch 58. The second switch also has on-hook 
and off-hook states. The state of the second switch determines whether a 
second level connection is established from the server 28 to one of the 
destination sites 22, 24 and 26. Consequently, when both of the switches 
54 and 58 are off-hook, the airphone 10 is in communication with one of 
the destination sites. 
The server 28 may also include a tone generator 60 that is used in the 
embodiment in which DTMF signals are generated or regenerated at the 
server. A tone generator is not critical, since the DTMF signals from the 
airphone 10 may be passed through the first and second switches 54 and 58 
to the PSTN 20. As will be readily understood by persons skilled in the 
art, digital signaling methods are utilized in a digital 
telecommunications network, such as an Integrated Services Digital Network 
(ISDN). Digital signals may be generated at the user's location or at the 
server. Of course, one of the two levels of connectivity may be an analog 
or digital connection using DTMF signals, while the other level is a 
digital connection using conventional digital signals. 
The server 28 also includes a tariff calculation device 62. This device 
determines the cost to the passenger for use of the server 28 in the 
manner described above. The tariff structure contained within the device 
62 may be connection based or time based. For example, there may be a 
connection fee of $1 or a per minute charge that is either fixed or 
determined by the distance to the destination site, i.e., a long distance 
charge. Again referring to the flat connection tariff of the exchange 
carrier 18 by the symbol "x," the server 28 is cost efficient only if 
Ax&gt;x+B, where A is the number of calls in a sequence utilizing the method 
of FIG. 2 and B is the total tariff charged for the use of the server 28 
for the calls. Thus, if the tariff structure of the server is connection 
based and the connection fee is "y," the use of the server is cost 
efficient only if Ax&gt;x+Ay. Cost efficiency for a time based tariff by the 
server may be considered with B=wz, where w is the total number of minutes 
for the calls and z is the per minute charge. Then, the use of the server 
is cost efficient only if Ax&gt;x+wz. 
While the invention has been described and illustrated as being used with 
an air-to-ground communications system, this is not critical. Rather than 
an exchange carrier, the provider that has a tariff structure based upon 
connections may be an Internet Service Provider (ISP). For example, 
telephone calls initiated using Internet telecommunications software may 
be made in sequence using the method of FIG. 2 and using an intermediate 
server that maintains the first level connectivity during the sequence of 
calls. In an alternative embodiment, the ISP may be used as the server 28. 
For example, the exchange carrier 18 of FIG. 1 may be connected to an ISP 
via the first connection level, with the second connection level being 
from the ISP to one of the remote sites 22, 24 and 26.