extension
Noun, Communication
serial number
Information Technology
(telephone) directory number
directory number
Communication
number engaged
Communication
(telephone) to dial a number
Verb
number portability (NP)
Noun
(slang) to pretend to be
Verb
to dead number to dial a number
Verb
automatic dialling device
look up a number in the phone directory
Verb
to dial a wrong number
Verb