152 lines
7.0 KiB
Plaintext
152 lines
7.0 KiB
Plaintext
|
||
II==================================II
|
||
][ ][
|
||
|| Incoming Trunk Service Observing ||
|
||
II - - - - II
|
||
][ ][
|
||
|| Written by ||
|
||
II II
|
||
][ The Egocutioner ][
|
||
|| ||
|
||
II of the II
|
||
][ ][
|
||
|| [+] PhoneLine Phantoms [+] ||
|
||
II - - - II
|
||
][==================================][
|
||
|
||
The ITSO (Incoming Trunk Service Observing) feature provides the ability
|
||
to perform service observing on incoming 2-wire trunk [per trunk signalling
|
||
or CCIS]. The ITSO feature provides a method to determine how effectively the
|
||
telefone system serves the customer. This assists the telefone co. in
|
||
maintaining network quality.
|
||
|
||
The intent of service observing is to evaluate the completion performance
|
||
of the office's subtending networks. All calls selected for observation must
|
||
originate from offices of equal or higher rank in the toll hierarchy and must
|
||
terminate in the area served by the toll office. The ESS switch randomly
|
||
selects calls for observation. Only one call can be monitored at any given
|
||
time for the ITSO feature. Equipment malfunctions, network overloads, or
|
||
other problems preventing call completion are detected. The calls are also
|
||
directly monitored for transmission quality. Each service observing position,
|
||
located in the SES (Service Evaluation System) bureau is capable of
|
||
monitoring calls.
|
||
|
||
The information required by the service observer is provided to the SES
|
||
bureau fro the ESS switch via a dedicated data link and a voice monitoring
|
||
channel. A 1200 baud data link is used to transmit call progress data and
|
||
control signals between the ESS switch and the SES bureau. The dedicated
|
||
one-way voice channel is required for monitoring voice transmission. The
|
||
interface is capable of monitoring one call at a time.
|
||
|
||
The SES has complete control over the SES/ESS interface. The observing
|
||
feature is a demand system where the demand originates with the SES. There
|
||
are 5 possible control messages that the SES can send to an ESS switch. They
|
||
are:
|
||
|
||
|
||
1. ENABLE- This message is accepted when the interface is in the
|
||
idle state. It directs the ESS switch to obtain the next observable call.
|
||
|
||
2. RELEASE- This message is used to release the present call and
|
||
return the interface to the idle state or to release the present test and
|
||
return to idle state.
|
||
|
||
3. TONE TEST- This message is used only if the interface is in the idle state. It causes a 1-milliwatt tone to be applied to the voice channel.
|
||
|
||
4. TERMINATION TEST- This messages is only accepted if the interface
|
||
is in the idle state. It causes a quiet termination to be applied to the
|
||
voice channel for 30 seconds (unless a RELEASE order is sent).
|
||
|
||
5. DATA ECHO TEST- This message is accepted only if the interface is
|
||
in the idle state. It sends a message to the ESS switch to verify the sanity
|
||
of the data channel. The ESS switch appends a unique 2-character header to
|
||
the received message and outputs the received message to the data channel.
|
||
|
||
There are 15 potential call progress messages that the ESS switch can
|
||
generate and send to the SES. They are:
|
||
|
||
1. SEIZURE- This message indicates that the ESS switch has found a
|
||
candidate call. If the SES does not receive this signal within a period of
|
||
time after being enabled, a RELEASE message is transmitted be the SES.
|
||
|
||
2. RELEASE ACKNOWLEDGE- This message is transmitted whenever the ESS
|
||
switch decodes a RELEASE signal deo the SES. The interface returns to the
|
||
idle state and the SES is allowed to attempt to observe a new call.
|
||
|
||
3. TERMINATION- This message is Xmitted when the interface returns
|
||
too the idles state due to an abnormal ending of the call observation in
|
||
progress, or when the tone or termination test times out.
|
||
|
||
4. INCOMING TRUNK DISCONNECT- This message is Xmitted to the SES for
|
||
every calling party on on-hook occurrence.
|
||
|
||
5. ON-HOOK- This message is Xmitted to the SES for every called party
|
||
on-hook occurrence.
|
||
|
||
6. OFF-HOOK- This message is xmitted to the SES for every called
|
||
party off-hook occurrence.
|
||
|
||
7. EMERGENCY- This message indicates an emergency announcement is
|
||
being applied to the calling party.
|
||
|
||
8. 60 IPM- This call progress message indicates that the busy tone
|
||
is being applied to the calling party.
|
||
|
||
9. 120 IPM- This call progress message indicates that recorder tone
|
||
is being applied to the calling party.
|
||
|
||
10. NO CIRCUIT AVAILABLE- This call progress message indicates that
|
||
a no circuit available is being applied to the calling party.
|
||
|
||
11. VACANT CODE ANNOUNCEMENT- This message indicates that a vacant
|
||
code announcement is being applied to the calling party.
|
||
|
||
12. RECORDER- This message indicates that a recorder announcement is
|
||
being applied to the calling party.
|
||
|
||
13. AUDIBLE RING- This message indicates that audible ringing is being
|
||
applied to the calling party. In the case of a locally terminating call, the
|
||
observer is not bridged onto the call until after answer and is therefore
|
||
unable to detect the actual audible ringing.
|
||
|
||
14. CALLED NUMBER DIGITS- This message contains the called number of
|
||
digits.
|
||
|
||
15. DATA ECHO TEST- This contains the DATA ECHO TEST message.
|
||
|
||
The 4 states of SES/ESS interface are as follows:
|
||
|
||
o Idle- This is the wait state of the interface. It is the state to
|
||
which the interface returns after tests and completing observations.
|
||
|
||
o Active- This state is entered only when the ESS switch receives an
|
||
ENABLE message from the SES. Service observing is performed in this state.
|
||
This state is maintained for no more than 3 minutes (2-wire trunks) after
|
||
seizure.
|
||
|
||
o Tone Test- This can only be entered from the idle state upon
|
||
receipt of a tone test order. In this state, a 1- milliwatt tone is applied
|
||
to the voice channel. The interface returns to the idle state upon the
|
||
RELEASE message or after a 30 second test.
|
||
|
||
o Termination Test- This state can only be entered from the idle
|
||
state upon the TERM. TEST message. In this state a quiet term. is applied to
|
||
the voice channel. The interface returns to the idle state upon the RELEASE
|
||
or after 30 secs.
|
||
|
||
Action to establish an observation is initiated when the SES send an
|
||
ENABLE message to the ESS switch. This message triggers the switch to begin
|
||
looking for an observable call. When the switch has found a call, the SEIZURE
|
||
and CALLED NUMBER DIGITS messages are transmitted to the SES.
|
||
|
||
From this point on, the SES observes the progress of the call using the
|
||
progress messages.
|
||
|
||
======================================
|
||
= All sysops are allowed to put this =
|
||
= file on their BBS's. =
|
||
======================================
|
||
|
||
(C) 1985 Sexy-Exy & PLP
|
||
|