A method of delivering voice and other unified communications services over the internet using the Session Initiation Protocol (SIP).
Here’s a more detailed explanation:
What it is:
SIP trunking replaces traditional phone lines by using internet connections to transmit voice, video, and messaging through a VoIP-enabled PBX. It enables businesses to make and receive calls using SIP trunks instead of physical phone circuits, providing a flexible and scalable communication solution.
How it works:
A SIP trunk is a virtual phone line provided by an ITSP (Internet Telephony Service Provider). It connects an on-premise or cloud PBX to the public telephone network (PSTN) via the internet. SIP handles call setup, management, and teardown, while the trunk supports multiple concurrent calls. Businesses can add or remove channels (call paths) without installing new hardware.
Benefits:
- Cost savings: Lower monthly bills and reduced long-distance or international call charges.
- Scalability: Easily add or remove call capacity without physical line installations.
- Flexibility: Supports voice, video, messaging, and presence on a single connection.
- Business continuity: Enables call routing to backups during outages or emergencies.
- Global reach: Make and receive calls from multiple locations using a centralized system.
Key components:
- SIP-enabled PBX: The phone system that manages call routing and features.
- Internet connection: A reliable broadband or dedicated link to carry SIP traffic.
- ITSP (provider): Supplies the SIP trunk and connects the system to the PSTN.
- SIP channels: Virtual lines that determine how many simultaneous calls can be made.
- Firewall/SBC: Security tools to manage SIP traffic and prevent unauthorized access.
Why it’s beneficial:
SIP trunking modernizes business telephony by making it more cost-effective, flexible, and scalable. It supports remote work, global expansion, and unified communications — while eliminating the limitations of outdated phone lines.