| AOCD | Advice Of Charge During Call | Gebühreninformation während und am Ende der Verbindung | 
| AOCE | Advice Of Charge End of Call | Gebühreninformation am Ende der Verbindung | 
| Automatic Private IP Addressing | ||
| AWS | Rufumleitung (früher Anrufweiterschaltung) | |
| BLF | Busy Lamp Field | Besetztlampfenfeld | 
| CAPI | Common ISDN Application Progamming Interface | |
| CCBS | Completion of Calls to Busy Subscriber | Rückruf bei besetzt | 
| CCNR | Completion of Calls on No Reply | Rückruf bei nichtmelden | 
| CD | Rufumleitung durch den Angerufenen | |
| CD (PR) | Call Deflection (Partial Rerouting) | Umleitung von Durchwahlnummern in der Vermittlungsstelle | 
| CFB | Call Forwarding on Busy | Rufumleitung bei besetzt | 
| CFNR | Call Forwarding on No Reply | Rufumleitung bei nichtmelden | 
| CFU | Call Forwarding Unconditional | Rufumleitung sofort | 
| CIDR | Classless Inter-Domain Routing | |
| CLIP | Calling Line Identification Presentation | Rufnummernanzeige | 
| CLIR | Calling Line Identification Restriction | Fallweise Unterdrückung der Rufnummer | 
| CNIP | Calling Name Identification Presentation | Namensanzeige | 
| CNIR | Calling Name Identification Restriction | Fallweise Unterdrückung des Namens | 
| COLR | Connected Line Identification Restriction | Anzeigeunterdrückung der Zielrufnummer beim Anrufer | 
| CoNDIS | Connection-Oriented Network Driver Interface Specification | |
| CSV | Comma-Separated Values | |
| CTI | Computer Telephony Integration | Computerunterstützte Telefonie | 
| Direct Dial In | Durchwahl | |
| Digital Enhanced Cordless Telecommunications | Digitales Funkfernsprechnetz | |
| DFÜ | Datenfernübertragung | |
| Dynamic Host Configuration Protocol | ||
| Differentiated Services Flag | ||
| DIP | Dual Inline Package | |
| Domain Name Service | ||
| DSCP | Differentiated Services Code Point | |
| DSL | Digital Subscriber Line | Digitaler Teilnehmeranschluss | 
| DSP | Digital Signal Processor | Digitaler Signalprozessor | 
| DTMF | Dual Tone Multi Frequency | Mehrfrequenzwahlverfahren (MFV) oder Tonwahlverfahren | 
| Dynamic DNS | Dynamisches DNS | |
| ECM | Error Correction Mode | Fehlerkorrekturmodus | 
| ELA | Elektroakustische Anlage | |
| EMV | Elektromagnetische Verträglichkeit | |
| Generic Access Profile | ||
| GSM | Global System for Mobile communication | Weltweites Mobilfunkverfahren | 
| HLC | High Layer Capability | |
| HTML | Hypertext Markup Language | |
| HTTP | Hypertext Transfer Protocol | Hypertext-Übertragungsprotokoll | 
| Hypertext Transfer Protocol Secure | Sicheres Hypertext-Übertragungsprotokoll | |
| Integrated Access Device | ||
| IP | Internet Protocol | Internetprotokoll | 
| IPUI | International Portable User Identity | Identifikationsnummer eines Mobilteils | 
| Impulswahlverfahren | ||
| Local Area Network | Lokales Netzwerk | |
| Lightweight Directory Access Protocol | Protokoll zum einfachen Zugriff auf Verzeichnisserver | |
| Light Emitting Diode | ||
| MAC | Media Access Control | |
| MWI | Message Waiting Indication | |
| Multi-Factor Authentication | Multi-Faktor-Authentifizierung | |
| Mehrfrequenzwahlverfahren | ||
| Multiple Subscriber Number | ||
| Network Address Translation | ||
| NF | Niederfrequenz | |
| Network Time Protocol | ||
| OTP | One Time Password | Einmalpasswort | 
| PCL | Printer Command Language | |
| Personal Identification Number | ||
| PMP | Protect Monitoring Point | |
| Power over Ethernet | ||
| PPP | Point-to-Point Protocol | |
| PTMP | Point-to-Multipoint | |
| PTP | Point-to-Point | |
| Quality of Service | ||
| RJ | Registered Jack | Genormte Buchse | 
| RSS | Really Simple Syndication | |
| RTP | Real-Time Transport Protocol | |
| SD | Secure Digital | |
| SDHC | Secure Digital High Capacity | |
| Session Initiation Protocol | ||
| SIPS | Session Initiation Protocol Secure | |
| SMTP | Simple Mail Transfer Protocol | |
| SRTP | Secure Real-Time Transport Protocol | |
| Simple Transversal of UDP over NATs | ||
| SW | Software | |
| TAE | Telekommunikations-Anschalte-Einrichtung | |
| Telephone Application Programming Interface | ||
| Transmission Control Protocol | ||
| Time-based One Time Password | Zeitlich begrenztes Einmalpasswort | |
| TSM | Türsprechmodul | |
| UAE | Universal-Anschlusseinheit | |
| User Datagram Protocol | ||
| Uml. | Rufumleitung | |
| Uniform Resource Locator | Einheitlicher Ressourcenzeiger | |
| USB | Universal Serial Bus | |
| USV | Unterbrechungsfreie Stromversorgung | |
| UTC | Coordinated Universal Time | |
| VMF | Voice Mail and Fax | |
| VoIP | Voice over Internet Protocol | |
| Virtual Private Network | ||
| Wide Area Network | ||
| XML | Extensible Markup Language |