Vapi on a Jamaican Number: Bring Your Own SIP Trunk with WOCOM

Vapi is built for developers. Instead of a fixed voice and model, you assemble an assistant from parts: a speech recogniser, a language model such as GPT or Claude, and a voice. Vapi supports bring-your-own SIP trunk, which is how you connect it to a Jamaican number you already own.

What You Need

• A WOCOM number on Cloud PBX or a SIP trunk.
• A Vapi account, an API key and an assistant you have already tested.
• SIP credentials from WOCOM (username, password and gateway address), if the assistant will place outbound calls.

Vapi's trunk setup is done through its API (https://api.vapi.ai), not the dashboard. Each step is a single request.

Step 1: Create the SIP Trunk Credential

Call POST /credential with "provider": "byo-sip-trunk". In gateways, list the WOCOM gateway address and set inboundEnabled so Vapi accepts calls from it. For outbound calls, add an outboundAuthenticationPlan with the authUsername and authPassword WOCOM issued. Set outboundLeadingPlusEnabled so numbers are sent as +1876.... Vapi returns a credential ID; keep it.

If WOCOM gives you an encrypted route, set the gateway's outbound protocol to tls/srtp.

Step 2: Add Your Jamaican Number

Call POST /phone-number with "provider": "byo-phone-number", your number in E.164 form (+1876XXXXXXX), and the credentialId from step 1. Then assign your assistant to that number, either in the same request or in the dashboard.

Step 3: Ask WOCOM to Route the Number

Send WOCOM support the following:

• The Jamaican number(s) you want answered by the AI, written in E.164 form (for example +1876XXXXXXX or +1658XXXXXXX).
• The platform's SIP address for inbound calls (shown below for this platform).
• Whether the AI also needs to place outbound calls, and from which number.
• Where calls should go if the AI hands a caller to a person: an extension, a ring group, or a mobile number.

For Vapi, the inbound address includes your credential ID:

sip:+1876XXXXXXX@<credential-id>.sip.vapi.ai

Signalling uses UDP or TCP on port 5060, or TLS on 5061. In the US region Vapi sends signalling from 44.229.228.186 and 44.238.177.138. WOCOM needs both on your trunk, because missing one is a known cause of intermittent 401 errors. Media arrives from changing addresses on UDP ports 40000–60000. Vapi advises against IP-only authentication unless the carrier gives a dedicated termination address, so expect WOCOM to use digest credentials for your outbound leg.

Step 4: Test an Outbound Call

Call POST /call/phone with your assistantId, the phoneNumberId from step 2, and a test destination such as your own mobile. The call should show your Jamaican number as the caller ID. If it fails with an authentication error, check the credentials in the outbound authentication plan first.

Transferring to Your Team

Give the assistant a transferCall tool with a destination of type sip and a sipUri such as sip:+1876XXXXXXX@your-wocom-gateway, or point it at an extension on your Cloud PBX. Vapi hands the call over with SIP REFER, so ask WOCOM to allow REFER on your route.

What It Costs (November 2026)

Vapi listed a platform fee of about US$0.05 per minute, with the speech, model and voice providers passed through at their own rates. It charges nothing extra for SIP. WOCOM bills the call itself. Because you choose every component, your real per-minute cost depends heavily on the model and voice you pick.

Things Vapi Does Not Document

Vapi's official documentation does not list the audio codecs or the DTMF method it uses on a bring-your-own trunk. Ask WOCOM to start with G.711, which every platform accepts, and test keypad input on a real call before you rely on it.

Is Vapi the Right Fit?

Choose Vapi if you have developers and want to swap models or voices freely. If you want a working receptionist this week without writing code, WOCOM AI is included with Cloud PBX. Compare the options in our platform comparison, or ask WOCOM to set up the trunk.