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- II==================================II
- ][ ][
- || Incoming Trunk Service Observing ||
- II - - - - II
- ][ ][
- || Written by ||
- II II
- ][ The Executioner ][
- || ||
- 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 servince 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 heirarchy 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 from 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 ony 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 recieved 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 recieve this signal within a period of time
- after being enabled, a RELEASE message is transmitted be the SES.
-
- 2. RELEASE AKNOWLEDE- 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 Xmited when the interface returns to the
- idle 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 progess message indicates that recoreder 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 stae to
- which the interface returns after tests and completing observations.
-
- o Active- This state is entered only when the ESS switch recieves an
- ENABLE message frm the SES. Service observing is performed in this
- state. This state is maintained for no moe 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
-
- Dedicated to Christi and Linda.
-
-
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