Egress network service monitor

Details Egress network service monitor Egress network service monitor

1997-08-20

2001-01-02

Hsu, Alpus H. (Department: 2738)

Multiplex communications

Fault recovery

C370S244000, C370S252000, C340S870030, C379S221050

Utility Patent

active

06169724

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a method and apparatus for passively monitoring egress service problems occurring on a telephone network.
BACKGROUND OF THE INVENTION
FIG. 1
shows a block diagram of a conventional long distance telephone network which includes interexchange carrier
5
, also known as an IXC, for routing long distance telephone calls. IXC
5
may be, for example, the network of any long distance carrier such as the AT&T long distance network.
As shown in
FIG. 1
, calling party
10
is connected to local exchange carrier
15
, also known as LEC, which includes a local switch, an example of which is the No. 5 electronic switching system, or No. 5 ESS. Local switches such as the No. 5 ESS are well known in the art. When the calling party
10
desires to make a long distance call by inputting a long distance telephone number, the LEC
15
is able to recognize this fact by examining the dialed number and searching for an appropriate prefix which indicates that the call is long distance call. When the LEC
15
determines that a call placed by the calling party
10
is a long distance call and it belongs to IXC
5
, the LEC
15
routes the call to IXC
5
. It should be noted that, because there are a variety of long distance carriers available, such as AT&T, MCI or Sprint, that could be IXC
5
in
FIG. 1
, the LEC
15
is preprogrammed to know which particular long distance carrier the calling party
10
has chosen for its long distance service. As a result, the LEC
15
is able to route the call to the appropriate IXC
5
.
As shown in
FIG. 1
, IXC
5
includes IXC originating switch (OS)
20
, IXC switched network
25
, and IXC terminating switch (TS)
30
. Originating switch
20
and terminating switch
30
are electronic switching systems such as a No. 4 ESS. Similarly, IXC switched network
25
is made up of a plurality of such electronic switching systems and network databases capable of instructing switches for routing the long distance call placed by the calling party
10
. As can be seen in
FIG. 1
, LEC
15
is connected to originating switch
20
which in turn is connected through the IXC switched network
25
via the transport network to terminating switch
30
, thereby providing the means through which a long distance call placed by the calling party
10
is routed through IXC
5
. The transport network consists of voice/data trunks and the “Signaling System 7” (SS7) signaling network.
The arrangement where signaling messages are transported by the voice/data trunks as audible tones is called “in-band” signalling. When a dedicated path exists to carry signalling messages as data packets, the signalling is said to be “out-of-band.” The best known examples of out-of-band paths are SS7 and ISDN, which stands for Integrated Services Digital Network.
Terminating switch
30
is connected to LEC
35
by voice/data trunk
33
, which in turn is connected to called party
40
. Similarly, terminating switch
30
may also be directly connected to private branch exchange
45
, also known as a PBX, by voice/data trunk
43
, which in turn is connected to called party
50
. Private branch exchanges are well known in the art and are generally any switching system owned or leased by a business or organization to provide both internal switching functions and access to the public telephone network. Thus, in
FIG. 1
, called party
40
is generally any member of the general public or a business whose access to IXC
5
is through LEC
35
, whereas called party
50
is generally a member of a business or organization whose access to IXC
5
is through PBX
45
.
Accordingly, a long distance call placed by calling party
10
intended for either called party
40
or called party
50
can be routed by the LEC
15
to the IXC
5
where it passes from originating switch
20
to IXC switched network
25
to terminating switch
30
. From terminating switch
30
, the call is routed to either called party
40
through voice data trunk
33
and LEC
35
or called party
50
through direct voice/data trunk
43
, bypassing LEC
35
, to PBX
45
, whichever is appropriate.
The part of the conventional long distance telephone network shown in
FIG. 1
in which a call is routed from terminating switch
30
to either called party
40
through LEC
35
or called party
50
through PBX
45
is generally called the egress network. The egress network is so named because it is the part of the network where a call leaves IXC
5
. In general, IXCs are very reliable. By “completes” it is meant that the call passes from the originating switch
20
to the terminating switch
30
. Most call failures, meaning that the call is not completed to either called party
40
or called party
50
, occur at the egress network, that is where the call leaves IXC
5
and is sent either to LEC
35
or PBX
45
, whichever the case may be.
There are several types of specific call failures occurring at the egress network, referred to herein as egress problems. Each egress problem may indicate a particular problem associated with either LEC
35
and called party
40
or PBX
45
and called party
50
. A number of different egress problems will be described in detail below.
A simple example of an egress problem is known as “line busy” and occurs when a call cannot be completed because the called party's line is in use. In the case where the called party is a business or organization, such a condition may indicate that the business or organization does not have enough lines to handle incoming traffic.
Another example of an egress problem is known as either “reorder” or “fast busy” and occurs when there is no available line for a particular call in voice data trunk
33
or
43
due to large call traffic. As a result, the calling party
10
will either hear an announcement indicating that the network is busy and instructing the called party
10
to call again at a later time (reorder) or will hear a fast busy tone (fast busy). Reorder and fast busy are problems that often occur when a business or organization launches a new promotion and a large number of callers attempt to simultaneously call a number provided in the promotion.
Another egress problem is known as “call abandoned” and is directly related to the behavior of the calling party
10
. In call abandoned, the call makes it to the called party
40
or called party
50
but the calling party
10
terminates the call before the called party
40
or called party
50
can answer the call. In the case where the called party is a business or organization, such a condition may indicate that either more agents are needed to answer calls more quickly or that the existing agents need to be trained to answer calls more quickly.
Still another common egress problem is known as “wink timeout.” When the terminating switch
30
is ready to route a call to either LEC
35
or PBX
45
, the terminating switch sends a signal to the LEC
35
or PBX
45
called a “wink” that tells the LEC
35
or PBX
45
to expect a call. In response, the LEC
35
or PBX
45
sends back a signal within a predetermined time frame indicating that it is ready to receive the call. In a wink timeout situation, the terminating switch
30
does not receive the signal from the LEC
35
or PBX
45
, and, as a result, never sends the call. The calling party
10
then hears an announcement instructing the calling party
10
to call again at a later time. Wink timeout egress problems may indicate an equipment problem at either LEC
35
or PBX
45
.
A final egress problem is known as “no supervision.” Under normal conditions, after the wink is sent out by terminating switch
30
and after the signal is received back from the LEC
35
or PBX
45
, the call is sent through to the called party
40
or called party
50
, whichever is appropriate, and as the call is answered, a second signal called answer supervision is sent from the LEC
35
or PBX
45
to the terminating switch
30
. This second signal triggers the charging mechanism. In no supervision situations, the answer supervision signa

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