14 Operator Assistance and Manual Services Early telephone networks were all manually operated.. In the public network human operators provide a ‘safety net’ of assistance and advice
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Operator Assistance and
Manual Services
Early telephone networks were all manually operated In the 1950s automatic networks began to take over, but even today they have failed to supplant all manual ‘assistance services’ In the public network human operators provide a ‘safety net’ of assistance and advice for customers, and in some private networks human PBX operators are still employed to answer incoming calls from the public network and to connect them to the required extension In this chapter we discuss the operator assistance services which form a critical supplement to automatic switched services
in meeting the high expectations of today’s telephone customer
14.1 MANUAL NETWORK OPERATION
In a manual network, the connection of caller to destination is carried out by human
operator This is done by plugging cords into individual line sockets or jacks, one jack
corresponding to each possible destination user Figure 14.1 illustrates an early manual switchboard, and Figure 14.2 a typical telephone used on such a manual network Instead of a numbered dial there is just a cradle for the handset and a magneto
generator to call the operator
The routine for making a call on a manual network is as follows The caller lifts the handset, and rings the magneto generator by turning the handle This has the effect of alerting the operator and lighting an opal (a light) on the operator’s switchboard
(Figure 14.1) In some cases, the operator was alerted merely by rattling the cradle This had the effect of flashing the opal There is an opal above each incoming line jack, indicating precisely which caller wishes to make a call To answer the request, the operator uses one of the cords mounted on the console part of the switchboard, which is
pulled out and plugged into the relevant jack socket immediately below the opal The
operator is now able to speak to the caller and ask for the name of the person he wishes
to call The operator records the caller’s name, the destination number and the time of
day, on a ticket for later billing of the caller The destination party is then alerted by the
operator, who rings his telephone with another hand-cranked generator The connection
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Networks and Telecommunications: Design and Operation, Second Edition.
Martin P Clark Copyright © 1991, 1997 John Wiley & Sons Ltd ISBNs: 0-471-97346-7 (Hardback); 0-470-84158-3 (Electronic)
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Opals
0
Schematic
l I /‘ Generator signalling
crank
Actual Figure 14.1 Early manual, or ‘sleeve control’ switchboard
is completed by plugging the other end of the cord into the jack of the destination party
In this way the pair of plugs and the cord connect the two corresponding line jacks to
caller and destination At the end of the call the caller replaces the handset, extinguishing
the opal On noticing this, the operator removes the plugs and cord from the jacks, ready
for use on another call
To make calls to customers on other exchanges the operator has a number of trunk
line jacks To use them, the operator must relay the call details to the operator on the
second exchange, and forward the connection The second operator either completes
the call or forwards it to another operator, as necessary In manual networks, setting up
telephone calls is highly labour-intensive, and in the early days the majority of the
workforce in public telephone companies were telephone operators
Semi-automatic telephony is the term used to describe connections which are set up by an
operator across an automatic network Semi-automatic telephony was common when
telephone networks were first being automated, especially when some exchanges had
been automated while others remained manual Callers on the manual exchange, who
wished to call others already connected to an automatic exchange, would have their calls
connected semi-automatically by the operator The caller would first contact the
operator, and the operator would then connect the call onward using special equipment
to control the automatic network rather than routing through further operators
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Figure 14.3 Inside of a hand generator signalling set, showing the magneto coils (Courtesy of
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Figure 14.4 Early operator switchboard (Courtesy of British Telecom)
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An explanation whlch will prevent many common misunderstandings
toucll with a Hop B-side operator who finds out if
Hop 3000 is free and helps the Museum operator to
connect the lina If conversely Hop 3000 wants The telephone lines in a large city are divlded Museum 605 it i5 a H o p A-side operator who
answers and gets into touch with a M w u m B - d e
Operator
into groups, called Exchanges
the B-s;dc ne of M Exchange d& a Central A-side operator gets into touch with a
directly only with Ringers up in that &change ; Central B-side operator
In every call therefore, two Post Office operators
B d e with those rung-up in that Exchange : - - - _ _
e.g Muscum 6 0 5 wants Hop 3000 In reality d c o y r ~ l h s t U I four -la : 1-0 Po.1 o(Lrr rnma
ud 1-0 .ancun-th.! i t k WO s m h r r i b s -d We m I.- .n
d d the u m ~ d P- 06ec I&+ ud H- llrr mea
- -
4
S
Figure 14.5 The exchange at work An extract from an early British Post Office publication providing an explanation which will prevent many common misunderstandings (Courtesy o f B T
Archives)
Ironically, in the reverse direction, any caller who was connected to an automatic exchange would have to dial a code to get hold of an operator to obtain a manual connection to any destination customer still connected to a manual exchange
Manual exchanges have progressively given way to today’s predominantly automatic
networks, but even today callers resort to dialling for assistance from the operator in a
number of instances
0 to call a user on a residual manual exchange (particularly in remote overseas
locations)
0 to receive assistance following difficulty on an automatic connection
0 to receive the answer to a general enquiry
0 to enquire for the directory number of another user
0 to make a call to the emergency services (fire, police or ambulance)
0 to make a special service call, such as a reverse-charge call (also known as a collect
call), or a personal call, etc
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In addition, many company switchboards and hotels still retain operators for the connection of incoming calls to individual extensions or hotel room numbers, despite the fact that direct diul-in (DDI, also direct inward dialling, DID) nowadays makes direct
dialling possible
If all we want is to get through to the operator and tell him we need assistance, the effect
of cranking the magneto is very much the same as dialling the right number on an automatic network On a sleeve-controlled switchboard (one using plugs, cords and jacks, as illustrated in Figures 14.1 and 14.4), incoming calls are indicated to the
Figure 14.6 Switchboard operators at work A picture giving an idea of the tangle of hands and leads the frenetic operation of manual exchanges (Courtesy of British Telecorn)
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operator by lighting the opals In modern ‘cordless’ operator switchrooms the call is administered by call queueing equipment or automatic call distribution ( A C D )
equipment This equipment stacks up calls in the order in which they are received, and allocates them to telephone operators in the switchroom as they become free from dealing with previous calls Operators simply press a button to indicate that they are ready to handle another call
While waiting in the queue for an operator to become free, the caller may hear ringing
tone, or may instead be given a recorded message, something like ‘this is the assistance service: an operator will deal with your enquiry shortly’ Recorded messages have the benefit of confirming that callers have ‘got through’, giving reassurance that they are not waiting in vain The recorded message also allows callers who have accidentally dialled the number for the operator service (when meaning to dial some other number),
to hang up their calls up and try again
Because connections made via the operator are multi-link rather than single link connections, special measures are required, to ensure that the end-to-end quality of the connection is acceptable, and to charge the customer correctly Callers are normally connected to the nearest switchroom This ensures that the end section connection is of the best available quality This part of the connection (i.e from caller to operator) is not normally automatically metered for charging purposes; the call charges are derived
either from paper tickets written by the operator, or from electronic tickets produced on the operator’s computer consoles
Operator switchrooms are designed to be efficient workplaces, and staff numbers and rosters are planned to meet customers’ call demand Just as an automatic telephone network must be provided with sufficient circuits to meet the traffic, so must the number
of positions manned by operators at any given time of day match the traffic demand at that time A useful quality target for staff providing an operator service is to aim to answer all calls within a given time (say 25 seconds), or perhaps to aim to answer 90%
of calls within say 15 seconds The latter statistic is often written in shorthand as PCAl5 = go%, i.e the percentage of calls answered in 15 seconds=90% PCA25 can also be used as a performance statistic (measuring the percentage of calls answered in 25
seconds), but the average caller on a public network who wants operator assistance, is not satisfied with such a long wait There is a relationship between the measured value
of PCA and the staffing level of the switchroom, the use of more staff generally increasing the PCA value Going to one extreme, to employ a very large number of operators queueing up to answer calls would ensure almost instantaneous answer At the other extreme, with too few operators it is the caller who does the queueing and waiting A modification of the Erlang formula presented in Chapter 30 is called the
Erlang waiting-time formula It can be used to calculate the number of operators required in a switchroom to keep the waiting time down to a target figure (i.e to cal- culate PCA values)
14.4 OPERATOR PRIVILEGES
In the onward connection of calls, operators may be given a number of special networking privileges They may have exclusive use of particular routes or of certain
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circuits within a route, to give their callers a better chance of getting through than normal customers (especially when the network is busy) This enables the operator to be
of real assistance to the caller in cases of difficulty, and furthermore reduces the likelihood of wasted operator time spent in futile repeat attempts Other privileges
explained below include manual hold, circuit monitoring and interruption, and forward
transfer However, with the increasing development and automation of networks, and
the small number of human operators available for network policing, these features are
becoming obsolete
Manual hold allows the operator to hold the connection even after the calling subscriber has replaced the handset This makes it possible to trace the origin of a malicious call in a case when a caller has given a false identity It also prevents the caller making any further calls This use of the facility is now largely susperseded by calling
line identity (CLZ) information in automatic networks and many networks today no
longer have the facility An alternative use of the manual hold facility permits tracing the
cause of faulty connections The ability to trace emergency service calls (e.g fire, police, ambulance) is of special importance
Circuit monitoring and interruption: sometimes the operator is given the facility to monitor or interrupt customers calls while in progress This can be useful in investi- gating customer complaints, including account discrepancies It can also be used to break in on conversation already in progress, when an important incoming call is received, and this would have been done historically if a trunk call was received while
only a local was in progress (hence the term for this facility, trunk o f e r )
Forward transfer: another facility becoming largely obsolete, the forward transfer facility allows the operator who has previously established a semi-automatic connection for the call, to request assistance from the operator at the destination exchange; inter-
national operators used it to provide language assistance (i.e translation) The oper-
ators might speak an intermediate language (typically French or English) between themselves and their mother tongue to their own customers to resolve any difficulties during call set-up (Example for person-to-person calls) The desired language of
assistance is indicated by a special digit called the language digit, which is inserted by
the originating operator’s exchange into the called customer’s dialled digit string during the signalling at call set-up This is discussed in more detail later in the chapter
14.5 TYPICAL ASSISTANCE SERVICES
As most calls are made automatically nowadays, operators need to provide only a range
of assistance services to complement the automatic service; here are some of the more
common ones
‘Station call’ service
A station call is the name given to an ‘ordinary’ call between two telephone stations,
when it is made via the operator A station call may be made (via the operator as opposed to automatically) either because the call cannot be dialled directly, or because customers prefer it, or perhaps because customers have had difficulty in getting
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through Another reason may be that the customer wishes to be rung back immediately
after the call has finished to be advised of the duration and charge ( A D C ) (also called
time and charges)
‘Reverse charge’ or ‘collect call’ service
For any of a variety of reasons, callers when travelling may not wish to pay for calls themselves, preferring to transfer the charges to the call recipients The service which
does this for them is the reverse charge or collect call service The reason for trans-
ferring the charge may be shortage of change when using a payphone, or to avoid
leaving ones host with a large telephone bill when staying away from home Whatever
the cause, collect call service must always be made via the operator Before receiving a
collect call, recipients are asked by the operator whether they are willing to accept the
call charges If so, the call is connected and an operator ticket records the call details in
the normal way, except that the bill is sent to the recipient rather than to the caller
A similar service, self-explanatory, is also sometimes available: ‘Bill call to third party’ (this might allow a payphone caller to charge the call to his home account)
‘Personal call’ service
(Also called a person-to-person call.) Sometimes callers may wish to contact particular
people who share their telephone with a number of others A caller may not want to
make an automatic call and pay for a connection, but to find out that the desired
individual is not available In these circumstances it is appropriate to make a personal
call, via the operator The caller gives the operator the name and telephone number of the individual required, and the operator then makes the call and checks that the right recipient is available to come to the telephone If so, the caller is charged from the
moment when the operator allows conversation to commence Usually either a
surcharge or a higher charge per minute of conversation is levied on personal calls If the person wanted is not available, the connection is cleared without conversation and the caller is not charged
‘Directory enquiry’ service
(Also called directory assistance.) To make an automatic call a caller must have the number of the destination telephone station Without that number the network has no indication of what connection the caller wants If the caller does not know it, perhaps because he has not called that particular person or company before, then one way of
‘looking-up’ numbers is to use the paper directory, issued to telephone customers This gives an alphabetic list of the names of all customers with their numbers However, the sheer number of customers nowadays has tempted many telephone companies to issue only a telephone directory covering the immediately surrounding geographical area The
operator directory enquiry (De) service provides a more comprehensive nationwide
service Access to the service in the normal way is by dialling an access code and waiting
in a queue at the nearest directory enquiry switchroom The operator looks up the num-
ber in the appropriate paper directory or by querying a computerized directory system
When the number is found it is given verbally to the caller, who then presumably follows
up the enquiry by placing a call over the automatic network Alternatively the operator