11 - ericssonhistory.com

A variety of special subscriber markings may be made at the exchange so
that callers to these numbers receive special printed codes.
A subscriber may not wish to receive traffic for an extended period, as for
example over a holiday period, and his line may have a plug inserted in such
a way as to control the equipment to return the characters ABS when the
number is called.
Similarly, a line which is not connected will return the C.C.I.T.T. standard
service code NP, indicating "not a working line."
The classification facility may be employed to provide separate networks
using the same switching equipment with complete or partial blocking of calls
between respective groups of subscribers.
For example, a network could be provided for civil or military authorities
with classification such that general subscribers to the telex service could not
call these outlets, although the outlets on the special network could call within
their own group or to subscribers of the general telex network.
Semi-automatic positions (Figure 6) have been provided at each transit
centre to cater for a further range of special requirements and to handleservice
difficulties, the combined facilities in one location being referred to
as a Telex Service Centre.
Fig. 6
Telex Service Centre — Manual assistance
position
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