CLI is also a
TLA for Calling Line Information,
information on a
phone call which tells the
recipient your
number. It is used by
ISPs and is required to be sent to use the Caller ID feature of some
phones and to use the
1471 number.
CLI can be
temporarily witheld by
dialling
141 before calling or it can be
permamently witheld by phoning a
special number maintained by
BT.
Please note: To the best of my knowledge this only applies in the UK.
cf. 1471 and 141.