Hello, Im new to Vapi. I just created an assistant, and on the configuration page, the latency estimation shows that Vonage has lower latency than Twilio. So I got a phone number from Vapi and associated the assistant to it, but Im not sure now if that phone number is using Twilio or Vonage. How can i check? I want it to use Vonage because it has the lowest latency.

To check if your phone number is using Twilio or Vonage, use the Vapi API to fetch the phone number details. Run the following cURL command (replace

<id>

with your phone number's ID and

<token>

with your API token):

bash
curl https://api.vapi.ai/phone-number/<id> \
  -H "Authorization: Bearer <token>"

Look for the

"provider"

field in the response; it will show

"twilio"

or

"vonage"

depending on your setup. Tip: You can list all your phone numbers and their IDs using the [List Phone Numbers API](https://docs.vapi.ai/api-reference/phone-numbers/list?explorer=true) if you don't know the ID. Sources: - [Get Phone Number](https://docs.vapi.ai/api-reference/phone-numbers/get) - [List Phone Numbers](https://docs.vapi.ai/api-reference/phone-numbers/list?explorer=true)

this is the response that i got

{"id":"dd7ddb26-3b3b-4c1b-8fef-e03b4f5c3dd0","orgId":"126af983-4297-4138-8285-305cd64269b0","assistantId":"ae35ee57-dd1f-4de1-94ae-199e220559ef","number":"+13469988785","createdAt":"2025-09-18T17:09:34.482Z","updatedAt":"2025-09-18T17:22:42.981Z","provider":"vapi","status":"active","providerResourceId":"00d7fdff-af5d-4723-83b3-869360cec2cc"}%

the provider shows vapi?? what does that mean?

"provider": "vapi" in your phone number response means your number is a native Vapi number, not a Twilio or Vonage SIP trunk. If you specifically want to use Vonage for lower latency, you'll need to provision a new number with the

"provider"

set to

"vonage"

during creation. Example:

json
"provider": "vapi" // Native Vapi number, not Twilio or Vonage

For more details, see the [Vapi Phone Number API docs](https://docs.vapi.ai/api-reference/phone-numbers/get). Sources: - [Get Phone Number](https://docs.vapi.ai/api-reference/phone-numbers/get) - [Advanced SIP Guide](https://docs.vapi.ai/advanced/sip)

but what does Vapi number use for SIP trunking? Twilio or Vonage? or does it use its own SIP trunking infra? in the latency estimation, there is no option of "Vapi sip trunking" https://cdn.discordapp.com/attachments/1418288604081553418/1418383110218977300/Screenshot_2025-09-18_at_4.47.50_PM.png?ex=68cdebb5&is=68cc9a35&hm=5773b061e3f29b40f3e8be83dc4137fbaf759d1e31e2be502d6a09aae73a610a&

Currently, the documentation does not specify whether a "vapi" provider number uses Twilio, Vonage, or Vapi's own SIP trunking infrastructure behind the scenes. If you need to guarantee Vonage or Twilio is used, you must provision a number with

"provider": "vonage"

or

"twilio"

during creation. For full transparency on the SIP backend for "vapi" numbers, please contact Vapi support directly, as this detail is not documented. Sources: - [Get Phone Number](https://docs.vapi.ai/api-reference/phone-numbers/get) - [Advanced SIP Guide](https://docs.vapi.ai/advanced/sip)

you must provision a number with "provider": "vonage" or "twilio" during creation.

: But in the UI, there is no option to choose SIP trunk provider when creating phone number