NEC Electra Elite 48/192 Features And Specifications Manual page 263

Issue 6
RELATED FEATURES
LIST
D - 54
This feature is not required for DTMF Single Line Telephones.
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These telephones send their own DTMF signals over the voice path
to the outside equipment.
Code Restriction, Outgoing Restriction, and LCR are not bypassed
¥
when this feature is used.
Feature
Number
D-9
E-3
S-6
Feature Name
Direct Inward Dialing (DID)
E&M Tie Lines (4-Wire)
Single Line Telephone Access
Electra Elite
DP to DTMF Switching