CPAAS and VOIP Terminology

For those who come from a new software development background and are new to the VOIP world, or for those who are new to both fields, we've put together some descriptions of common terms and response codes to serve as a reference when interacting with the NetSapiens API.

You can find another general-purpose glossary for industry-standard terms on our other documentation site, here:

https://documentation.netsapiens.com/support/614107-netsapiens-glossary

Here you will find another glossary of general telecom- and VOIP-related terms to familiarize yourself with in the event that you are new to these fields:

https://documentation.netsapiens.com/voip-101/854694-voip-glossary-know-your-terms

Term/Concept	Description
REG (Registered)	A fundamental SIP concept where devices/agents establish presence. Involves SIP REGISTER messages, authentication, expiry mechanisms. Critical for call routing, load balancing, and system health.
OOS (Out of Service)	Device/agent unavailability state. Caused by network issues, hardware/software failures, maintenance, or registration expiration. Important for monitoring duration, frequency, and impact.
device_aor (Address of Record)	Canonical SIP URI address (sip:user@domain or sips:user@domain). Can include transport parameters. Varies between user-agents (no 'sip:' prefix) and device-agents (full URI).
FQDN (Fully Qualified Domain Name)	Complete domain name for VoIP hosts. Used for SIP server identification, certificate validation, DNS SRV records, and load balancing.
CDR (Call Detail Record)	Detailed call metadata including timestamps, addresses, duration, routing, quality metrics, and termination reasons. Also tracks jitter, packet loss, codec info, and transfers.
SIP Methods	Core protocols: INVITE (session start), BYE (session end), REGISTER (registration update), SUBSCRIBE (request updates), NOTIFY (deliver updates), OPTIONS (capability queries).
SIP Responses	Categories: 1xx (Provisional), 2xx (Success), 3xx (Redirection), 4xx (Client Error), 5xx (Server Error), 6xx (Global Error).
RTP (Real-time Transport Protocol)	Protocol for audio/video delivery over IP. Handles sequencing, timing, media mixing, SSRC identification, payload types.
ICE (Interactive Connectivity Establishment)	NAT traversal framework using STUN/TURN servers, candidate gathering, and connectivity checks.
Presence	Real-time availability status system with states: Available, Busy, Away, Do Not Disturb, and custom states.