<!-- Source: https://docs.vinsi.ai/phone-connections/overview -->
# Connecting Your Phone System

How VINSI AI agents connect to the phone numbers and phone systems you already use — Twilio, Telnyx, Mitel, 3CX and Zoom Phone.

Created: September 18, 2026

Updated: September 18, 2026

## Overview

An AI agent needs a phone number that callers can reach, and a way to hand calls to your people. You can give it a number from VINSI, connect a number you already have with a carrier, or connect the phone system your team already works in. Which route suits you depends mostly on **where your numbers live today** and **whether the AI needs to reach your staff by extension**.

## Ways to Connect

| Method                               | What it is                                                                                                                                                      | Set up by                           |
| ------------------------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------- |
| **A number from VINSI**              | Buy a number in **Phone Numbers → Add Phone Number**. It runs on the Telnyx network and is ready to use straight away.                                          | You, in a few minutes               |
| **SIP trunk from your carrier**      | Keep your number with your own carrier account (Twilio, Telnyx and similar) and connect it with **Phone Numbers → Add SIP Trunk**.                              | You, following the carrier guide    |
| **Phone system through VINSI's SBC** | A SIP connection between your office phone system and VINSI's Session Border Controller, so the AI can transfer to extensions and call out through your system. | VINSI, with your phone system admin |
| **Call forwarding**                  | Your phone system forwards incoming calls to a VINSI number. No SIP setup at all.                                                                               | Your phone system admin, in minutes |

## Which One Fits

| You use                      | Recommended route                                       | AI transfers to                               | Guide                                                                                      |
| ---------------------------- | ------------------------------------------------------- | --------------------------------------------- | ------------------------------------------------------------------------------------------ |
| Nothing yet                  | A number from VINSI                                     | Any phone number                              | [Setting Up Phone Numbers](https://docs.vinsi.ai/ai-phone-agents/setting-up-phone-numbers) |
| Twilio                       | SIP trunk (Elastic SIP Trunking)                        | Any phone number                              | [Twilio](https://docs.vinsi.ai/ai-phone-agents/elastic-sip-trunking)                       |
| Telnyx (your own account)    | SIP trunk                                               | Any phone number                              | [Telnyx](https://docs.vinsi.ai/phone-connections/telnyx)                                   |
| Mitel MiVoice Business / MBG | Phone system through VINSI's SBC                        | Extensions and phone numbers                  | [Mitel](https://docs.vinsi.ai/phone-connections/mitel)                                     |
| 3CX                          | Call forwarding, or VINSI's SBC for extension transfers | Phone numbers (extensions with the SBC route) | [3CX](https://docs.vinsi.ai/phone-connections/3cx)                                         |
| Zoom Phone                   | Call forwarding                                         | Direct numbers and call-queue numbers         | [Zoom Phone](https://docs.vinsi.ai/phone-connections/zoom)                                 |

## Terms Used on These Pages

| Term                | Meaning                                                                                                                                   |
| ------------------- | ----------------------------------------------------------------------------------------------------------------------------------------- |
| SIP trunk           | An internet phone line between two phone systems. See [What is SIP Trunking?](https://docs.vinsi.ai/ai-phone-agents/what-is-sip-trunking) |
| Origination         | Calls coming _in_ from the phone network. Your carrier sends them to VINSI's address.                                                     |
| Termination         | Calls going _out_ to the phone network. VINSI sends them to your carrier's address.                                                       |
| SBC                 | Session Border Controller — a SIP gateway that sits between two phone systems and handles security, addressing and audio.                 |
| DID / direct number | A phone number that reaches one person or queue directly, rather than an internal extension.                                              |
| E.164               | The full international number format VINSI uses, e.g. +18005551234.                                                                       |

## Current Limits

- **SIP trunks take US and Canada numbers.** The Add SIP Trunk form accepts `+1` followed by 10 digits. Contact VINSI if you need to connect numbers from other countries.
- **Phone system connections through the SBC are set up with VINSI.** They aren't self-service yet, because each system needs its dial plan and security matched on both sides.
- **Call forwarding covers incoming calls only.** The AI transfers and dials out through VINSI, so it reaches your staff on their full phone numbers rather than internal extensions.