- I (In-Phase)
- i-mode (Internet Mode)
- IDEN (Integrated Digital Enhanced Network)
- IF (Intermediate Frequency)
- ILEC (Incumbent Local Exchange Carrier)
- Imaging
- IMAP4 (Internet Messaging Access Protocol)
- IMEI
- IMSI (International Mobile Subscriber Identity)
- IMT-2000 (International Mobile Telecommunication 2000)
- IMTA (International Mobile Telecommunications Association)
- IMTS (Improved Mobile Telephone Service)
- Industrial Telecommunications Association (ITA)
- InFLEXion
- Information Skyway
- Institute of Electrical and Electronic Engineers (IEEE)
- Integrated Circuit (IC)
- Integrated System
- Intellectual Property Rights (IPR)
- Intelligent Network
- Intelsat (International Telecommunications Satellite Consortium or International Telecommunications Satellite Organization)
- Inter-Symbol Interference (ISI)
- Interactive Video Data Service (IVDS)
- Interconnect
- Interconnect facility
- Interconnection
- Interexchange Carrier (IXC)
- Interface
- Interference
- Interleaving
- International Record Carrier (IRC)
- International Shortwave Broadcast Station
- International Standards Organization (ISO)
- International Telecommunications Union (ITU)
- Internet capability
- Internet Protocol (IP)
- Internet Protocol version 6 (IPv6).
- Interoperability
- Intersatellite link
- Interworking Function (IWF)
- iPod
- IS (Interim Standard)
- IS-136 EIA (Interim Standard 136)
- IS-2000 EIA (Interim Standard 2000)
- IS-41 (Interim Standard 41)
- IS-54 EIA (Interim Standar 54)
- IS-95 EIA (Interim Standard 95)
- ISDN (Integrated Services Digital Network)
- ITU-T International Telecommunications Union (Telecommunications standarization sector)
- iTunes
- IXLT
I
