DDD:Domestic Direct Dialing,國內直撥電話業務。關聯詞:IDD
DDI:Direct Dialling-In,直接撥入
DECT:Digital Enhanced Cordless Telecommunication,數字增強無繩通信
DID:Direct Inward Dialling,直接撥入。關聯詞:DOD
DOD:Direct Outward Dialling,直接撥出。關聯詞:DID
DTMF:Dual Tone Multi-Frequency,雙音多頻