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1991-12-30
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Recommendation E.424
TEST CALLS
1 General
Test calls carried out manually or automatically to assess the functioning
of international circuits of connections are of four types:
a) Type 1 test call
A test call conducted between two directly connected international
centres to verify that the transmission and signalling on an
international circuit of a given group are satisfactory.
b) Type 2 test call
A test call conducted between two international centres not directly
connected to verify transit operational facilities of an intermediate
international centre.
c) Type 3 test call
A test call from an international centre to a subscriber type number in
the national network of the distant country, generally as a result of a
particular kind of fault.
d) Subscriber-to-subscriber type test call1)
A subscriber-to-subscriber type test call is a test call from a test
equipment having the characteristics of an average subscriber line in
one national network to a similar equipment in the national network of
a distant country.
Test calls types 1, 2, 3 and subscriber-to-subscriber test calls must not
interfere with customer traffic. If, however, test calls contributing a
significant load on a part of a network are to be made, prior advice should be
given to the other Administration(s) concerned. Types 1 and 2 test calls for
preventive maintenance should be conducted during light load periods. Types 1 and
2 test calls should be conducted as and when required for the investigation and
clearance of faults.
Type 3 test calls should be conducted only after adequate testing has been
done by means of type 1 or 2 test calls and after the distant Administration has
made the necessary check in its national network. Type 3 test calls should be
conducted during light load periods.
In order to find faults in last-choice equipment, circuit multiplication
equipment or in-circuit multiplexing equipment, it may be necessary for tests to
be carried out at the time when the traffic load approaches the full capacity of
the route under test. The agreement of the distant network analysis point will be
necessary before this test is carried out.
Subscriber-to-subscriber type test calls can be made by agreement of the
network analysis point in the countries concerned.
Normally, unless there is a specific agreement between the Administrations
concerned, subscriber-to-subscriber type test calls would be considered for fault
location after:
1) verifying that there are no evident faults in the international
switching centres involved that would cause the poor quality of service
or subscriber complaint being investigated;
2) verifying that type 1 or type 2 test calls have been made on the
international circuits that might have been involved;
3) verifying that there are no evident faults in the national network from
the outgoing exchange to the international centre in the originating
country;
4) verifying that there are no evident faults in the national network in
the distant country, from the international centre to the called
exchange.
When test calls are undertaken from the international centre to a
subscriber number to verify that there are no evident faults in the national
network, such calls should be routed through the international centre on the same
path as a normal incoming international call. Using the test access facilities in
the international centre could route calls via a different path thereby masking a
fault.
When subscriber-to-subscriber type test calls are made, the network
analysis point in the two countries should consider such factors as:
i) the expected nature of the fault;
1) Recommendation M.1235 describes the use of automatic-to-subscriber test calls in more
detail.
Fascicle II.3 - Rec. E.424 PAGE1
ii) international accounting agreements;
iii) the need for making the test calls in the busy hour;
iv) the possibility of causing or aggravating congestion at the time the
calls are made.
The responding equipments used for subscriber-to-subscriber type test
calls could be those used for maintenance of the national network.
2 Results of test calls (see Table 1/E.424)
TABLE 1/E.424
Results of test calls
International outgoing exchange: Type of test call
Type 1 a)
Circuit group: Type 2 a)
Type 3 a)
Servicesemi-automatic a) Sub-to-Sub a)
automatic a)
Period from to
Number Percentage
Category Subtota Total Subtota Total
l l
1.Satisfactory tests . . . . . .
2.Signalling and charging faults . . . . . .
2.1Wrong number
PAGE2 Fascicle II.3 - Rec. E.424
. . . . . .
2.2No tone, no answer . . . . . .
2.3Absence of a backward line signal . . . . . .
2.4Other faults . . . . . .
3.Transmission faults . . .
. . .
3.1Conversation impossible . . . . . .
3.2Call overamplified or underamplified . . . . . .
Fascicle II.3 - Rec. E.424 PAGE1
3.3Noise . . . . . .
3.4Fading . . . . . .
3.5Crosstalk . . . . . .
4.Congestion . . . . . .
5.Other faults . . . . . . . . . . . .
. . . . . .
Tests carried out
PAGE2 Fascicle II.3 - Rec. E.424
. . . 100
Tests procedure followed (apparatus used, destination of calls, etc.)
a) Detele whichever is inapplicable.
Fascicle II.3 - Rec. E.424 PAGE1