| ACD | Contact center queue (Automatic Call Distribution) |
| ACW/Wrap up | Processing of the call agenda (After Call Work) |
| AUX | The state when the agent does not receive calls (is engaged in other activities) |
| Agent/Operator | User (phone line) serving the contact center queue |
| Called/Calling | The called party for whom the call is intended (this is a specific telephone number) |
| Caller/Callee | The calling party that initiates the call (dials the phone number and waits for connection) |
| Call Forward | Automatic call forwarding to another phone |
| Call Pickup | Picking up a ringing call on another phone (internal line) |
| Call Transfer | Manual transfer of the call to another phone, Blind: immediate transfer, With Consultation/Attended: incl. of the conversation with the person to whom |
| CDR | Overview of phone calls |
| Dialplan | Numbering plan, all phone number ranges that can be called |
| Extension/Flap | Internal telephone number (line) to which it is possible to call |
| External call | Outgoing or incoming call to the PBX |
| FXO | Analog telephone interface, port on the gateway to which the state line is connected |
| FXS | Analog telephone interface, the port on the gateway to which the telephone device is connected |
| ISDN | Digital telephone interface, BRI: two speech channels, PRI or E1: 30 speech channels |
| Incoming/Inbound | Incoming call to telephone or PBX |
| Internal call | Call within the branch telephone exchange |
| IVR | Voice menu in which the caller can choose where to continue their call (Interactive Voice Response) |
| MoH | Music on Hold, music played to the caller while on hold or on hold in ACD |
| Outgoing/Outbound | Outgoing call from telephone or PBX |
| Pattern | Range of phone numbers, X represents any digit, eg 1XX (range 100 to 199) |
| Provisioning | Providing IP phone configuration, mostly using the TFTP protocol |
| PBX | Telephone Exchange (Private Branch eXchange) |
| RTP | Voice Path (Real-time Transport Protocol) |
| SBC | SIP and RTP gateway (Session Border Controller) - serves to separate voice networks (application firewall) and to route calls |
| SIP | Protocol for signaling (connecting) telephone calls (Session Initiation Protocol) |
| Trunk | Used to connect the branch telephone exchange to the public telephone network or another PBX |
| BLF | Allows you to monitor the status of selected telephone lines (ringing, busy, idle) using lights |