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