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Recommendation E.422
OBSERVATIONS ON INTERNATIONAL OUTGOING TELEPHONE CALLS
FOR QUALITY OF SERVICE
1 Objectives concerning Table 1/E.422 and Table 2/E.422
1.1 Th of service observation in the
international service is to assess the quality of service obtained
by the calling subscriber. Consequently, it is essential to have
factual or objective recording of observations (i.e., successful
and unsuccessful calls), and to present them in the form of a table
(see Table 1/E.422 for manual or semi-automatic observations and
Table 2/E.422 for automatic observations).
2 Manual or semi-automatic observations (Table 1/E.422)
2.1 Table 1/E.422 should be capable of being completed through the use of a
wide range of observation facilities, i.e. from the simple to the sophisticated.
TABLE 1/E.422
Observations of international outgoing telephone calls for quality of service
Country of origin Point of access:
Outgoing international exchange National side
Group of circuits Link circuits
Serviceautomatic a) Outgoing side
semi-automatic a)
Period: from to Time of observations
Category Number Percentage
Subtot Total Subtot Total
al al
1.Calls successfully put through (see note 1) ... ...
2.Ring tone received but no answer
Fascicle II.3 - Rec. E.422 PAGE1
... ...
3.Unsuccessful calls: Positive indication of
congestion, including subscriber busy, from beyond
the outgoing international exchange. Visual ... ...
signal, tone or recorded announcement
3.1Subscriber busy/congestion indicated by ... ...
visual signal
3.2Subscriber busy/congestion indicated by ... ...
busy/congestion tone
3.3Congestion indicated by a recorded ... ...
announcement
PAGE8 Fascicle II.3 - Rec. E.422
TABLE 1/E.422 (cont.)
4. Unsuccessful calls: Other visual signals, tones ... ...
or recorded announcements, not positively
identified as category 3 or 8
4.1Visual signal received ... ...
4.2Tone received ... ...
4.3Recorded announcement received ... ...
5.Unsuccessful calls for other technical reasons ... ...
5.1Wrong number obtained ... ...
5.2Abandoned due to very poor speech ...
transmission
Fascicle II.3 - Rec. E.422 PAGE1
...
5.3No tone, no answer after waiting ... ... ...
seconds
5.4Reception of answer signal when the called ... ...
party does not reply
5.5Other failures of a technical kind ... ...
6.Unsuccessful calls due to incorrect handling by ... ...
the calling party
6.1Wrong number dialled ... ...
6.2Incomplete number ... ...
PAGE8 Fascicle II.3 - Rec. E.422
6.3Call prematurely abandoned before receipt ... ...
of signal, tone or announcement (within less than
... seconds)
6.4Call prematurely abandoned after receipt of ... ...
ring tone (within less than 30 seconds)
6.5Other failures due to incorrect handling ... ...
7.Total calls monitored (categories 1-6) ... 100
8.Unsuccessful calls: Positive indication of
failure from outgoing international exchange
8.1Congestion on outgoing international ...
circuits
8.2All other indications ...
Fascicle II.3 - Rec. E.422 PAGE1
9.Successful calls with defects. These calls are ...
included in category 1
9.1Non-reception of answer signal on ...
chargeable calls
9.2Call with impaired intelligibility but not ...
abandoned
9.3Other calls with defects but not abandoned ...
a) Delete whatever is inapplicable
Note 1 - A successful call is one that reaches the wanted number and allows conversation
to proceed. All successful calls are entered in category 1. However, a successful call may
or may not have noticeable defects. Successful calls with noticeable defects should also
be entered in category 9.
Note 2 - With the exception noted above for categories 1 and 9, the results of one call
observation should be entered under one category only, namely the most appropriate one
from 1 to 6.
Note 3 - Administrations should periodically exchange necessary information to interpret
the observation data recorded under categories 4.1, 4.2 and 4.3.
PAGE8 Fascicle II.3 - Rec. E.422
2.2 Specialized training of observers should be kept to a minimum.
2.3 The table should be self-explanatory so that reference to detailed
how-to-complete instructions is unnecessary.
2.4 The major categories should be selected such that:
- they identify the major factors adversely affecting the quality of
service;
- they are suitable for the centralized processing of observation
results.
2.5 To permit the orderly collection of data for human factors studies to
identify sources of difficulty in customer use of the international (automatic)
telephone service, Recommendation E.427 contains an additional table to
Table 1/E.422.
3 Comments concerning the use of Table 1/E.422
3.1 Table 1/E.422 summarizes observations made on outgoing automatic and/or
semi-autom traffic, on a
country of origin to a country of destination basis. A separate
form should be used for each country of destination, and if
required, for each group of circuits to which traffic to a country
of destination has access at the outgoing international exchange
(or exchanges). It is not necessary to make observations on both
automatic and semi-automatic services. An Administration may select
the service to be observed, provided that the service is the
majority of the traffic to the country of destination.
3.2 For an explanation of the point of access, see Recommendation
E.421, S 4.1.
3.3 The result of each call observed should be entered only under
the most appropriate category. In the case of several faults on one
call, the most significant cause of failure should be entered.
3.4 In completing Table 1/E.422 reference should be made to the
following explanations.
4 How to fill in Table 1/E.422
Category 1 - To ensure objective recording and to avoid producing a biased
sample resulting from the exclusion of calls which require subjective assessment,
the successful call is defined as a call that reaches the wanted number and
allows conversation to proceed. All non-abandoned calls are entered into category
1 and of these calls those which are subjectively adjudged to be defective are
also entered into category 9. Thus it is required of the observer to make two
entries for successful calls with noticeable defects.
Enter in category 1 then, calls successfully put through. This includes
answered calls for which a clearback signal is received after some words have
been spoken, without knowing for what reason the call is abandoned. If it is
observed that the caller has dialled a wrong number, the call will be entered
under 6.1. Category 1 will also include calls put through correctly to operator
positions, information services, or to machines replying in place of the
subscriber or to their equivalents.
Category 2 - Enter in this category calls on which ring tone was heard but
the subscriber did not answer before the attempt was abandoned, the caller having
waited at least 30 seconds after commencement of ring tone before clearing
forward. (See category 6.4 if the call was abandoned less than 30 seconds after
ring tone commenced.)
Fascicle II.3 - Rec. E.422 PAGE1
Category 3 - Enter in this category all unsuccessful calls in which a
positive indication of subscriber busy or congestion beyond the outgoing
international exchange had been encountered, either by visual signal, tone or
recorded announcement. Congestion encountered on common control equipment should
be entered in this category as well (e.g. no "proceed-to-send" signal). Where a
positive indication of these conditions has not been received, enter in category
4.
Categories 3.1, 3.2 and 3.3 are entered for the specific indication
received.
When more than one indication is received, e.g. visual signal and audible
tone, only one entry should be made. In this case, the preferred order of entry
should be tone, announcement, visual signal.
Category 4 - Enter in this category all other indications on unsuccessful
calls whether by visual signal, tone or recorded announcement that cannot be
positively identified and entered in category 3 or 8.
Categories 4.1, 4.2 and 4.3 are entered for the specific indication
received.
When more than one indication is received, e.g. visual signal and audible
tone, only one entry should be made. In this case, the preferred order of entry
should be tone, announcement, visual signal.
Category 5 - Enter in this category those calls which fail for technical
reasons not included in categories 3, 4 and 8. Category 5 subdivides as follows:
Category 5.1 - Calls on which the wrong number was obtained, although the
caller dialled correctly.
Category 5.2 - Calls abandoned by the caller because of very poor speech
transmission, although the answer signal was received. (See category 9.2
if speech transmission is poor but the call is not abandoned.) In some
countries observers may be required to cease listening immediately after
conversation is established, thus reducing the number of calls that would
be reported in this category.
Category 5.3 - Calls on which the dialling information was correctly and
completely sent, but the caller received no signal, tone or announcement
before abandoning the call, having waited for at least the specified
period before clearing forward.
The value of this time period left open under this category should be
filled in by the Administrations of the originating country according to
its experience in this matter. The prescribed value may differ depending
on the international destination. It is, however, recommended to limit the
number of such different quoted periods to a maximum of three values (e.g.
10, 20 or 30 seconds or any other value considered pertinent by the
Administrations concerned).
Category 5.4 - Calls on which an answer signal was received, although the
called subscriber did not answer.
Category 5.5 - Call failures due to technical reasons which are unable to
be entered in categories 5.1 to 5.4. These should be very few, if any, and
this category is provided in case they do arise. All possible information
about these failures should be supplied as an attachment to the summary of
the table. This category includes calls abandoned due to reception of a
clear-back signal while connecting with the extension number (PBX).
Category 6 - Enter in this category all unsuccessful calls which have
failed due to incorrect handling by the caller (subscriber or operator). Category
6 subdivides as follows:
Category 6.1 - Calls on which it was determined that the number which
should have been dialled was different from the number actually dialled.
Category 6.2 - Calls on which it was determined that the number dialled
had insufficient digits to be successful.
PAGE8 Fascicle II.3 - Rec. E.422
Category 6.3 - Calls on which the digital information was correctly and
completely sent, but the caller abandoned the call without receiving any
signal, tone or announcement, and without waiting for at least the
specified period.
The value of the time period left open under this category should be
filled in by the Administrations of the originating country according to
its experience in this matter. The prescribed value may differ depending
on the international destination. It is, however, recommended to limit the
number of such different quoted periods to a maximum of three values (e.g.
10, 20 or 30 seconds or any other value considered pertinent by the
Administration concerned).
The value quoted under category 6 must be the same as that quoted under
category 5.
Category 6.4 - Calls prematurely abandoned after receipt of the ringing
tone on which the caller disconnected less than 30 seconds after the
ringing tone commenced. (See category 2 if the call was abandoned after
more than 30 seconds had elapsed from the time of commencement of ringing
tone.)
Category 6.5 - Calls which failed due to incorrect handling by the caller
which cannot be classifed under categories 6.1 to 6.4. All possible
information about these failures should be supplied as an attachment to
the summary of the table. As in categories 5.5, these should be very few,
if any.
Category 7 - Enter in category 7 the number of calls monitored (categories
1-6).
Category 8 - Category 8 will be useful for those Administrations which
observe on the national side of the outgoing international exchange. (See
Recommendation E.421, S 4.1.) Positive indications of failure, congestion or
other, are to be entered here. They are not to be included with categories 1-6,
which give the data for calls monitored for category 7.
Thus, when category 8 is viewed with categories 3 and 4 a more complete
picture is provided of quality of service received by the caller.
Category 9 - Entries in category 9 are for successful calls (entered in
category 1) which encountered defects, but which were not abandoned. They are
thus automatically included in the total of category 7.
Category 9.1 - Enter here chargeable calls for which no answer signal was
received. If abandonment should be detected on such calls, enter in
category 5.5.
Category 9.2 - Enter here calls on which poor speech transmission was
observed, but the call was not abandoned. (See category 5.2 if the call
was abandoned.) All possible information about these calls should be
supplied as an attachment to the summary of the table. Note that in some
countries observers may be required to cease listening immediately after
conversation was established, thus reducing the number of calls that would
be reported under this category.
Category 9.3 - Enter here calls encountering switching, signalling or
transmission defects, but which were not abandoned and which cannot be
classified under categories 9.1 or 9.2.
5 Automatic observations (Table 2/E.422)
Considering the limitation of abilities of automatic observation equipment
(for example, automatic observation equipment cannot understand announcements)
and the variety of signals used in signalling systems, the table recommended for
CCITT Signalling System No. 5 is given below.
TABLE 2/E.422
Automatic observations of international outgoing telephone calls for quality of service
Country of origin Point of access:
Outgoing international exchange National side
Group of circuits Link circuits
Serviceautomatic a) Outgoing side
semi-automatic a)
Period: from to Time of observations
Category Number Percentage
Subtot Total Subtot Total
al al
1.Calls successfully put through
Fascicle II.3 - Rec. E.422 PAGE1
... ...
2.Ring tone received but no answer ... ...
3.Unsuccessful calls: Positive indication of
congestion, including subscriber busy, from beyond
the outgoing international exchange. Visual ... ...
signal, or tone
3.1Subscriber busy/congestion indicated by ... ...
visual signal
3.2Subscriber busy/congestion indicated by ... ...
busy/congestion tone
4.Unsuccessful calls: Other visual signals, tones ... ...
or recorded announcements, not positively
identified as category 3 or 8
4.1Tone received ... ...
PAGE8 Fascicle II.3 - Rec. E.422
4.2Recorded announcement received ... ...
5.Unsuccessful calls for other technical reasons ... ...
5.1No tone, no answer signals after waiting ... ...
... seconds
5.2Reception of answer signal when the called ... ...
party does not reply
5.3Other failures of a technical kind ... ...
6.Unsuccessful calls due to incorrect handling by ... ...
the calling party
6.1Call prematurely abandoned before receipt ...
of signal, tone or announcement (within less than
... seconds)
Fascicle II.3 - Rec. E.422 PAGE1
...
6.2Call prematurely abandoned after receipt of ... ...
ring tone (within less than 30 seconds)
6.3Other failures due to incorrect handling ... ...
7.Total calls monitored (categories 1-6) ... 100
8.Unsuccessful calls: Positive indication of
failure from outgoing international exchange
8.1Congestion on outgoing international ...
circuits
8.2All other indications ...
9.Successful calls with defects. These calls are
PAGE8 Fascicle II.3 - Rec. E.422
included in category 1 ...
9.1Non-reception of answer signal on ...
chargeable calls
9.3Other calls with defects ...
a) Delete whatever is inapplicable.
6 Comments concerning the use of Table 2/E.422
6.1 Table 2/E.422 summarizes observations made on outgoing automatic and
semi-automatic traffic, on a country of origin to a country of destination basis.
A separate form should be used for each country of destination, and if required,
for each group of circuits to which traffic to the country of destination has
access at the outgoing international exchange (or exchanges).
6.2 For an explanation of the point of access, see Recommendation E.421, S
4.1.
6.3 The result of each call observed should be entered only under the most
appropriate category. In the case of several faults on one call, the most
significant cause of failure should be entered.
6.4 As the function of sound analysis by automatic observation equipment is
not concerned with the signalling system used and since some signalling systems
e.g. Signalling System No. 6 have more information exchanged in the signalling
system than those of sound signals, it is expected that the proposed table will
be applied to all signalling systems for the present.
6.5 In completing Table 2/E.422 reference should be made to the following
explanations.
7 How to fill in Table 2/E.422
Category 1 - The succes s defined as a call
that allows conversation to begin between subscribers, or allows to
begin sending facsimile or data. This includes calls put through to
operator positions, information services, or to machines replying
in place of the subscriber or to their equivalents. In other words,
the successful call is such that the automatic observation
equipment detected voice on both sending and receiving lines, or
that it detected sending tone of facsimiles or data, or that it
detected voice on the receiving line after receipt of answer
signal.
Category 2 - This category includes those calls for which the
automatic observation equipment detected ringing tone,
but there was no answer signal and the clear-forward
signal was sent 30 seconds after the detection of
ringing tone.
Category 3 - Enter in category 3 all unsuccessful calls for
which a positive indication of subscriber busy or congestion beyond the outgoing international
exchange has been encountered, either by visual signal (busy-flash
signal) or by tone (also includes no "proceed-to-send" signal).
Category 4 - Enter in category 4 unsuccessful calls for which
the automatic observation equipment
detected a tone, but could not classify it, or the equipment
detected announcement (that is, it detected voice on receiving line
without answer signal).
Category 5 - Enter in category 5 those calls which failed for
technical reasons not included in categories 3, 4 and 8. Category 5
subdivides as follows:
Category 5.1 - Calls on which the dialling information was completely sent, but the automatic observation
equipment received no signal, tone or announcement and it
received a clear-forward signal after a specified period. The
value of this time period left open under this category should
be filled in by the Administrations of the originating country
according to its experience in this matter. The prescribed
value may differ depending on the international destination.
It is, however, recommended to limit the number of such
different quoted periods to a maximum of three values (e.g.
10, 20 or 30 seconds or any other value considered pertinent
by the Administrations concerned).
Category 5.2 - Calls on which an answer signal was received,
although the called subscriber did not answer. In other words,
calls for which the automatic observation equipment received
Fascicle II.3 - Rec. E.422 PAGE1
an answer signal, although it detected no voice on receiving
line.
Category 5.3 - Failed calls due to technical reasons which are
unable to be entered in categories 5.1 and 5.2. For example, a
call for which there was a busy-flash signal after receiving
ringing tone.
Category 6 - Enter in category 6 all unsuccessful calls which have failed
due to incorrect handling by the caller (subscriber or operator). Category 6
subdivides as follows:
Category 6.1 - Calls on which the dialling information was completely
sent, but the automatic observation equipment received no signal, tone or
announcement and it received a clear-forward signal within a specified
period. (For this period, see category 5.1 above.)
Category 6.2 - Calls prematurely abandoned after receipt of the ringing
tone on which a clear-forward signal was received less than 30 seconds
after the ringing tone was detected.
Category 6.3 - Calls which failed due to incorrect handling by the caller
which cannot be classified under categories 6.1 and 6.2. For example, a
call for which the automatic observation equipment received an answer
signal after receiving ringing tone, and then the ringing tone stopped,
but the equipment could not detect any voice either on the sending line or
the receiving line.
Category 7 - Enter in category 7 the number of calls monitored (categories
1-6).
Category 8 - Category 8 will be useful for those Administrations which
observe on the national side of the outgoing international exchange. Positive
indications of failure, congestion or other, are to be entered here.
Category 9 - Entries in category 9 are for successful calls (entered in
category 1) which encountered defects. Category 9 subdivides as follows:
Category 9.1 - Calls on which no answer signal was received, but the
conversation was begun.
Category 9.2 - Calls which encountered switching or signalling defects,
but on which the conversation was begun.
PAGE8 Fascicle II.3 - Rec. E.422
