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ATT DEFINITY Communications System Generic 3 Instructions Manual
ATT DEFINITY Communications System Generic 3 Instructions Manual
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Look Ahead Interflow Issue 3 March 1996 3-847 Look Ahead Interflow Basics When one switch has an overload of incoming calls, it may b ecome necessary to route some of the incoming calls to another switch so they can be handled more efficiently and will not be lost. Look Ahead Interflow is simp ly the means used to determine whether the other switch is able to handle the calls. When preset thresholds at one switch are reached (for example, the numb er of calls in queue), and another call comes in, that switch c hecks to see if another switch can handle the call. The other switch then checks to make sure it can handle the call. If it can, the call is sent to that switch. If it cannot, the sending switch must try to process the call in another way, such as intraflowing to a backup split or placing a second Look Ahead Interflow call attempt to an alternate b ackup switch. Look Ahead Interflow is accomplished through the use of call vectors and their associated c ommands. These call vectors are a dministered for both the sending and receiving switches: nSending Switc h Vectors at the sending switch use conditional goto vector commands to test outflow threshold conditions, and route-to commands to send the call to another switch. The sending switch may provide alternate treatment if the call is denied at the receiving switch. nReceiving Switch Vectors at the receiving switch use conditional goto vector commands to do inflow checking and decide whether the call should be accepted or denied. Call acceptance is accomplished when commands such as queue-to main, check-backup, announcement, collect, and wait-time are reached in the call vector at the receiving switch. (See Table 3-67 for more information on acceptance conditions.) Call denial is accomplished when commands such as busy and disconnect after announcement none are reached in the call vector at the receiving switch. Two-Switch Look Ahead Interflow Configuration An examp le of a Two-Switch Look Ahead Interflow configuration is shown in Figure 3-24. The operation of the sending switch and the receiving switch are described in the following paragraphs.
Feature Descriptions 3-848Issue 3 March 1996 Figure 3-24. Two-Switch Look Ahead Interflow Connections Sending Switch Operation As with standard vectoring interflow, outflow checking and outflow is accomplished by means of conditional goto and route-to vector commands. There are no unique vector commands for this feature. If the Look Ahead Interflow option is enabled, and the call is being routed over an ISDN-PRI facility, interflow will automatically be carried out on a look ahead basis. (There is one exception to this rule. A route-to with cov y vector command will never result in a Look Ahead Interflow call.) For Look Ahead Interflow calls, vector processing does not immediately terminate when ISDN-PRI facilities are successfully seized for a route-to operation. Instead, the call remains in any hunt group or split queues at the sending switch until it is accepted at the receiving switch. Any audible feedback initiate d by the vector continues. If an a gent becomes available at the sending switch during a Look Ahead Interflow call attempt, the caller is immediately connected to the available agent, and the Look Ahead Interflow call attempt is dropped. The sending switch attempts to interflow the call to the receiving switch. We will assume a successful ISDN-PRI connection. One of the following then occurs. nCall Acceptance If a call acceptance message is returned by the receiving switch before any call denial message, the sending switch will terminate vector processing, disconnect any tones a p plied by the sending switch vector and remove the call from all queues at the sending switch. Control of the call is now passed to the receiving switch. INCOMING CALLSSENDING SWITCH SWITCHISDN - PRI RECEIVING MAIN SPLITBACKUP SPLIT PRIVATE NETWORK
Look Ahead Interflow Issue 3 March 1996 3-849 nCall Denial If a call d enial message is returned by the receiving switch b efore any call acceptance message, the sending switch will drop the Look Ahead Interflow call attempt and continue vector processing at the next vector step. nTimeout If a call acceptance or call denial message is not returned from the receiving switch within 10 seconds after the receiving switch receives the Look Ahead Interflow call request, the Look Ahead Interflow attempt is dropped and the sending switch continues vector processing at the next vector step. An examp le of an outflow vector used by a sending switch is as follows: 1. queue-to main split 3 pri m 2. announcement 1001 3. goto step 5 if oldest-call-wait in split 3 pri l > 30 4. wait-time 20 secs hearing music 5. route-to with cov n if unconditionally 6. announcement 1002 7. wait-time 120 secs hearing music 8. goto step 6 if unconditionally If split 3 has no available agents, Step 1 will place the caller in split 3’s queue at medium priority. In Step 2, an announcement is played apologizing for the delay. Step 3 does the outflow checking. If calls have b een queued up for longer than 30 seconds, the vector goes to Step 5 and does Look Ahead Interflow. Otherwise, the vector proceeds to Step 4 and music is played for 20 seconds. If the c all is still not answered after 20 seconds, then the vector goes to Ste p 5 and attempts Look Ahead Interflow. In Step 5, a Look Ahead Interflow call is placed to a remote switch. If the call is a c cepted, the incoming call is removed from split 3’s queue and control of the call is passed to the receiving switch. If the call is denied, the caller remains in q ueue and hears announcement 1002 followed by music. Receiving Switch Operation When the receiving switch receives the Look Ahead Interflow request, the call routes to a VDN, the VDN maps the call to the receiving switch’s inflow vector and vector processing begins, starting with inflow checking. Inflow checking is accomplished with conditional goto commands in the inflow vector. The decision to accept or reject a call can be based on checks of the following: nNumber of staffed agents nNumber of available agents
Feature Descriptions 3-850Issue 3 March 1996 nTime of day/week nNumber of calls in split’s queue nNumber of seconds that the oldest call has been waiting in the split’s queue nRolling Average Speed of Answer (G3V4 and later releases) nActive VDN calls (G3V4 a n d later releases) nExpected Wait Time (G3V4 and later releases) nANI (G3V4 and later releases) nII-digits (G3V4 and later releases) Once inflow checking is complete, acceptance of the look ahead call can b e accomplished by executing any of the vector commands shown in Table 3-67. Table 3-67. Call Acceptance Vector Commands and Qualifications Call Acceptance Vector Commands Qualification announcement Announcement available or Queued for announcement or Retrying announcement check-backupCall terminates to agent or Call queued for sp lit c ollect Always converse-on VRU answers the call or Call queued to converse sp lit disconnect With announcement and announcement available or With announcement and queued for announcement or With announcement and retrying announcement messaging Successful or Queued Continued on next page
Look Ahead Interflow Issue 3 March 1996 3-851 If, during inflow checking, the receiving switch decides that it is unable to accept the look ahead call, call denial can be accomplished by executing any of the vector commands listed in Table 3-68. Use of the busy command is recommended over the disconnect command to allow for compati bility with network services. q ueue-to main Call terminates to agent or Call queued for sp lit route-toTerminates to valid local destination or Successfully seizes a non-PRI trunk or Results in Look Ahead Interflow call attempt and the call is accepted by the far end switch wait-time Always (exc ept wait-time hearing i-silent which is neutral) Table 3-68. Call Denial Vector Commands and Qualifications Call Denial Vector Commands Qualification busy Always disconnect With no announcement or With announcement but announcement unavailable Table 3-67. Call Acceptance Vector Commands and Qualifications — Continued Call Acceptance Vector Commands Qualification Continued on next page
Feature Descriptions 3-852Issue 3 March 1996 The vector commands shown in Table 3-69 do not generate either call acceptance or denial messages and are considered neutral. The following is an example of an inflow vector used by a receiving switch. 1. goto step 6 if staffed-agents in split 12 is < 3 2. goto step 6 if queued-calls in split 12 pri l is > 4 3. queue-to main split 12 pri h 4. wait-time 30 secs hearing music 5. stop 6. busy Steps 1 and 2 do inflow checking. For split 12, if the numb er of staffed agents is less than three or the number of calls in queue is greater than 4, call control is transferred to Step 6 which denies the look ahead call. Otherwise, Step 3 will queue the call for split 12 and return a call acceptance message to the sending switch. Table 3-69. Neutral Vector Commands and Qualifications Neutral Vector Commands Qualification adjunct routing Always announcement Announcement unavailable check-backup The call neither terminates nor queues converse-on Call neither terminates nor queues goto step Always goto vector Always messaging Failure q ueue-to main The call neither terminates nor queues route-to Unsuccessful termination or Trunk not seized or Look Ahead Interflow call denied by far end switch sto p Always wait-time hearing i-silentAlways (New with G3V4)
Look Ahead Interflow Issue 3 March 1996 3-853 Tandem Switch Configuration Tandem Look Ahead Interflow can be accomplished with Call Vectoring and Look Ahead Interflow active at the receiving switch by using route-to commands that contain external destinations which use ISDN-PRI facilities. An examp le of a tandem Look Ahead Interflow configuration is shown in Figure 3-25. The o peration of the sending switch and the receiving switch are d escribed in the following paragraphs. Figure 3-25. Look Ahead Interflow Using a Tandem Switch Sending Switch Operation The sending switch is unaware of the fact that its Look Ahead Interflow call is being tandeme d to an alternate switch. The operation of the sending switch in the tandeming configuration is exactly as for the two switch configuration. Tandem Switch Operation If the receiving switch executes a route-to command that routes the call over an ISDN facility before call acceptance, the route-to command is performe d on a ‘‘look ahead’’ basis in the same manner as a sending switch. If the call is accepted at the far end switch, a c ceptance is p assed to the sending switch, and control of the call is passed to the far end switch with tandeming of the original calling party information and the original DNIS name. If the call is denied, the next step of the tandem switch vector is executed. If a denial is retained by the Tandem Switch to the originating switch, the next vector step on the originating switch is executed. INCOMINGSENDING SWITCH SWITCHISDN - PRI MAIN SPLITBACKUP SPLIT FAR END SWITCHISDN - PRITANDEM CALLS ALTERNATE BACKUP SPLIT
Feature Descriptions 3-854Issue 3 March 1996 Great c are should b e taken by the vector programmer to ensure that the sending switch is not used as a backup location for the tandem switch or any of the far end switches. If administered in this manner, all trunk facilities could be tied up by a single call. Example of Tandem Switch Vector An examp le of a tandem switch vector follows: 1. goto ste p 4if staffed-agents in split 30 > 5 2. route-to if unconditionally 3. busy 4. queue-to main split 30 pri m 5. announcement 2300 6. wait-time 60 secs hearing music 7. goto step 5 if unconditionally Step 1 checks the inflow thresholds. If the inflow criteria is acceptable, Step 4(queue-to main) will p rovide acceptance to the sending switch. Therefore, Steps 5-7 provide a typical q ueuing-wait sc heme. If the call c annot b e handled at split 30, the route-to command checks another Look Ahead Interflow equip ped switch on a ‘‘look ahead’’ basis. If the far end switch rejects the call, the busy command causes a denial to be sent to the sending switch. If the far-end switch accepts the call, then the acceptance is relayed back to the sending switch. Far End Switch Operation The far end switch is also unaware that tandeming has taken place. The far end switch will operate the same as in the case of the receiving switch in the two-switch configuration. Display Information Answering Agent’s Display The DNIS information in the Look Ahead Interflow information element provided by ISDN-PRI is presented on the answering agent’s display on the receiving switch if the Look Ahead Interflow o ption is enabled, the c all routes to a VDN, and the DNIS name is not blank. The DNIS name included in the Look Ahead Interflow information element is as follows: nIf this is a tandemed look ahead call, then the Look Ahead Interflow DNIS information from the original look ahead call is used. nIf no redirection has taken place at the sending switch, the VDN name according to display override rules are used.
Look Ahead Interflow Issue 3 March 1996 3-855 nIf redirection has occurred, display override rules do not take effect. The Look Ahead Interflow DNIS will contain the original VDN name, or, if multiple VDNs are accessed, the name of the VDN last accessed by means of a route-to vector command. VDNs that ma p to vectors which place Look Ahead Interflow calls must have their ISDN CPN prefixes administered. Failure to administer the ISDN CPN prefix results in a Look Ahead Interflow DNIS of all spaces being sent and disp layed on the answering agent’s terminal. Originator’s Display On internal calls, the originator’s display is the same as for normal Call Vectoring. However, the following precaution should be taken to prevent undesirable display up dates from being received during Look Ahead Interflow call attempts. Since most customers would not like the originator’s display to be updated on each Look Ahead Interflow call attempt, Look Ahead Interflow calls should normally go out over trunk groups with the “Outgoing Display” field set to no. Audible Feedback Audible ringback is provided to the caller when a wait-time hearing ringback vector command is executed or when the call is successfully route d to a local destination. Care must be taken by the vector programmer not to confuse callers by providing incompatible audible feedback at both the outflow and inflow vectors. For exam ple, providing ringback at the receiving switch might be confusing to the caller if ringback and an announcement had previously been supplied by the sending switch. Normally a vector for human callers should initially return audible feedback such as ringback, music, or an announcement so that the caller knows that the c all g ot through. However, vectors which do not return any audible feedback may be used in situations where VDNs are a c cessed b y machines and audible feedback may be inappropriate and/or undesirable. The receiving switch vector does not initially give Look Ahead Interflow calls any locally denied termination treatment such as busy tone, reord er tone, or intercept tone. The caller does not hear these because feedback is still being provided by the sending switch vector. Considerations The receiving vector should not be administered to have calls route back to the vector for the outflowing switch. If administered as such, all trunk facilities may eventually be tied up with the same call.
Feature Descriptions 3-856Issue 3 March 1996 All calls routed over ISDN-PRI facilities by means of route-to number with cov n and route-to digits with cov n vector commands on a switch where the Look Ahead Interflow option is enabled are treated as Look Ahead Interflow call attempts. Initial audible feedback may be provided to the caller before interflow is attempted. Therefore, another audible feedback from the receiving switch may not be appropriate. For exam ple, a caller hearing ringback on the sending switch may be confused if music is suddenly a p plied when the call interflows to the receiving switch. Delay in interflowing should be minimized. An acceptance or denial response should be provided to the sending switch as quickly as possible by the vectors on the receiving switch. If, d uring Look Ahead Interflow, the call terminates to an agent on the sending switch or the call is abandoned by the originator, the Look Ahead Interflow call is dropped, vector processing terminates, and the original call is removed from all split queues. It is p ossible d uring a Look Ahead Interflow call attempt for a call to b e accepted at a receiving switch, by means of a queue-to main or check-backup command, an instant before the call is answered at the sending switch. If the acceptance message is d elayed due to signal propagation d elay, there could b e a short interval when the c aller and the receiving switch agent are connected. An agent at the sending switch may then answer the call before the a c ceptance message arrives at the sending switch. The caller would then be disconnected from the receiving switch agent and connected to the sending switch a gent. These phantom calls can be eliminated by appropriate programming of the inflow vector. If calls are accepted by wait-time or announcement vector commands before the call is q ueued to a split, there is no possibility of a phantom call occurring. It is perfectly acceptable for a vector to route a call over an ISDN-PRI facility to a destination which is not a VDN. As far as the sending switch is concerned, this call will be treate d as a Look Ahead Interflow call even though this is not in fact the case. Generic ISDN p rocessing at the receiving switch will cause the call to be accepted. The DNIS name and any other information in the Look Ahead Interflow information element is ignored. If a Look Ahead Interflow call terminates to a VDN on a receiving switch where the Look Ahead Interflow option is not enabled, intelligent interflow will result. However, the DNIS information in the Look Ahead Interflow information element is ignored and no intelligent interflow to far-end switches is possible. Interactions The following features interact with the Look Ahead Interflow feature: