Glossary
What is a SIP trunk?
The internet connection that replaced physical phone lines, and why it matters when you add an AI receptionist.
The short answer
What is a SIP trunk?
A SIP trunk is a virtual phone line that carries calls over the internet between your phone system and a phone carrier, using SIP (Session Initiation Protocol). It replaces physical phone lines: one trunk can carry several calls at once, and phone numbers are assigned to the trunk rather than to a copper line. Businesses use SIP trunks to connect an office or cloud phone system, or a voice application, to the public phone network.
How it works
A SIP trunk is an account with a carrier, not a cable. Your phone system connects to it over the internet, and the carrier connects it to everyone else's phones.
- The carrier gives you the trunk's connection details and assigns your phone numbers to it.
- Your phone system, or a voice application, connects to the trunk with those details.
- Incoming calls to your numbers arrive over the trunk; outgoing calls leave through it.
- The plan sets how many calls can run at the same time, often called channels.
Example
A law firm with a phone system in its office moves from physical lines to a SIP trunk from its carrier. Its numbers stay the same, and the system now sends and receives calls over the office internet connection. Later, the firm connects an AI receptionist to the same trunk to answer its after-hours calls.
What it means for a small business
If your phone system already runs on a SIP trunk, Daber AI can take calls over it, and you keep your numbers and your phone system. If your provider doesn't offer a SIP trunk, call forwarding works with any line: forward every call to the agent's number, or only the ones you don't answer.
Questions
What is the difference between a SIP trunk and VoIP?
VoIP is the general idea of carrying calls over the internet. A SIP trunk is one specific way of doing it: a connection between a phone system and a carrier that uses the SIP protocol.
How many calls can a SIP trunk carry at once?
It depends on how many channels your carrier's plan includes and on your internet bandwidth. Ask the carrier how many simultaneous calls your trunk allows.
Do I need a SIP trunk to use an AI receptionist?
No. Most small businesses either forward their existing number or use the number the agent gets on sign-up. A SIP trunk is for businesses that already run their own phone system and want calls to reach the agent through it.
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