signal
加入词篮digital technology
sensor
image sensor
optical sensor
remote sensor
monitor
termination
actuator
monitoring
scrutiny
telephone
telephone directory
telephone exchange
telephone tapping
receiver
recipient
handset
beeper
videophone
telephony
operator
telephonist
wireless
radio
acoustic aid
acoustic amplifier
teleprinter
telesales
telemarketing
long-distance call
local call
area code
phone
car phone
cellular phone
cellphone
mobile phone
payphone
phone booth
pay station
phonecard
phone box
directory toll
switchboard
extension
dialling code
dialling tone
telegram
express telegram
deferred telegram
cable
telegraph
post
postcode
post office
postbag
postbox
postal order
postal service
postmaster
postage
mailbag
mailbox
letter-box
mailing
mailing list
mail order
airmail
letter
letterhead
postcard
post card
notepaper
letter box
letter of credit
send-off
dispatch
despatch
messenger
ambassador
ambassadress
postman
postmen
stamp
stamp collecting
envelope
postmark
sender
addressee
introducer
delivery
deliverer
deliver system
courier
mailman
parcel
registered letter
letter-scales
