X.21bis

The Physical Layer specification within the X.25 protocol suite. X.21bis defines call control procedures, synchronization mechanisms, and the mechanical and electrical parameters for cables and connectors, which are similar to RS-232. X.21bis supports full-duplex (FDX) transmission at speeds from 9600 bps to 64 kbps. See also FDX, Physical Layer, synchronization, and X.25.

• European Telecommunications Network Operators’ Association (ETNO)
• European Telecommunications Standards Institute (ETSI)
• Européenne des administrations des Postes et des Télécommunications or CEPT)
• EV-DO (EVolution-Data Optimized)
• EV (EVolution-Data Optimized)
• Evolution-Data Optimized (EV-DO or EV)
• EVRC (Enhanced Variable Rate Vocoder)
• Excess Burst Size (B )
• Excess Information Rate (EIR)
• exchange
• exchange
• exchange
• Exchange Carriers Standards Association (ECSA)
• exclusive hold
• Expedited Forwarding (EF)
• Explicit Congestion Notification (ECN)
• extended band (E-Band)
• Extended Binary Coded Decimal Interchange Code (EBCDIC)
• Extended Erlang B (EEB)
• extended service set identifier (ESSID, or SSID)
• extended superframe (ESF)
• Extended TACS (ETACS)
• Extended Total Access Communications System (ETACS)
• Extensible Markup Language (XML)
• Extensible Messaging and Presence Protocol (XMPP)