> ## Documentation Index
> Fetch the complete documentation index at: https://docs.voiceinfra.ai/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# SIP Phone Numbers: Provision, Import, or Use Any Carrier

> Provision new SIP DID numbers, import from custom SIP trunks, or connect any carrier with VoiceInfra's flexible SIP integration.

VoiceInfra gives you three ways to put a phone number to work with your AI agents: provision a brand-new number directly through the platform (Currently, support USA, Australia, and Singapore), import existing numbers from Twilio or Telnyx in one click, or connect any carrier via a custom SIP trunk and define the DID numbers. All three options land in the same dashboard, route to the same AI agents, and require no changes to what your customers already dial.

## Choose Your Number Source

<CardGroup cols={3}>
  <Card title="Provision a New Number" icon="phone-plus" href="/docs/channels/sip-numbers">
    Choose your country and area code, complete payment, and receive a fully managed SIP DID number within 2–5 minutes. Currently, numbers available for US, Singapore, and Australia. Other regions coming soon. 
  </Card>

  <Card title="Import from Twilio" icon="arrow-down-to-bracket" href="/docs/channels/twilio">
    Keep your existing Twilio numbers exactly where they are. One-click import pulls your numbers directly into VoiceInfra. No porting required.
  </Card>

  <Card title="Import from Telnyx" icon="arrow-down-to-bracket" href="/docs/channels/telnyx">
    Keep your existing Telnyx numbers exactly where they are. One-click import pulls your numbers directly into VoiceInfra. No porting required.
  </Card>
</CardGroup>

## Provision a New Number US Number

<Steps>
  <Step title="Open the phone number provisioning screen">
    In the VoiceInfra dashboard, go to **Settings → Phone Numbers → Add Number**.
  </Step>

  <Step title="Select Provision VoiceInfra Number ">
    Select the State and Click Search Available numbers.
  </Step>

  <Step title="Pick a number from the list">
    Browse the available numbers returned for your selection. Click the number you want to reserve it.
  </Step>

  <Step title="Complete payment">
    Confirm the monthly subscription. Your number provisions automatically, it is ready to use within 2–5 minutes.
  </Step>

  <Step title="Assign to an AI agent">
    Navigate to the number in your dashboard and select the AI agent that handles inbound calls, outbound calls, or both.
  </Step>
</Steps>

## Connect a Custom SIP Trunk

<Steps>
  <Step title="Open the custom SIP trunk screen">
    Go to **Settings → Phone Numbers → Add Phone Number → Custom SIP Number**.
  </Step>

  <Step title="Enter your DID number details and Inbound-Outbound trunk configuration details">
    Configure the DID number, we supported standard E.164 format. Provide the SIP URI supplied by your carrier (e.g., `sip.yourcarrier.com`). This is the endpoint VoiceInfra uses to send and receive calls. From your trunk provider point the traffic to VoiceInfra's SIP address **sip.voiceinfra.ai.** 
  </Step>

  <Step title="Select a transport protocol">
    Choose **UDP** (fastest, widest compatibility), **TCP** (reliable delivery), **TLS** (encrypted, recommended for security-sensitive deployments), or **AUTO** to let VoiceInfra negotiate the best option.
  </Step>

  <Step title="Set SIP authentication credentials">
    Enter the username and password provided by your carrier for SIP trunk authentication.
  </Step>

  <Step title="Configure IP whitelisting">
    Add your carrier's IP ranges in CIDR notation (e.g., `203.0.113.0/24`). VoiceInfra only accepts inbound SIP from these ranges, blocking unauthorized traffic.
  </Step>

  <Step title="Set inbound/outbound routing ">
    Specify which AI agent handles inbound calls and outbound calls on this trunk.
  </Step>
</Steps>

## Advanced Inbound Routing

Take full control over which calls reach your AI agents.

* **Allowed numbers whitelist** — restrict inbound calls to a specific list of caller IDs, rejecting all others
* **IP restrictions (CIDR)** — filter inbound SIP traffic by source IP range
* **Multi-agent routing** — assign different AI agents to different numbers, or separate inbound and outbound agents on the same number

##

## Technical Specifications

| Feature              | Detail                                            |
| -------------------- | ------------------------------------------------- |
| Transport protocols  | UDP, TCP, TLS, AUTO                               |
| Provisioning time    | 2–5 minutes                                       |
| Media encryption     | SRTP supported                                    |
| Uptime SLA           | 99.9%                                             |
| IP whitelisting/Auth | IP Auth, IP Auth with username/password supported |
| PBX Extension        | Reverse register AI Agent on any PBX via SIP      |

## Frequently Asked Questions

<AccordionGroup>
  <Accordion title="Can I keep my existing phone number?">
    Yes. If your number is on Twilio or Telnyx, import it with one click — no porting required. For other carriers, configure a custom SIP trunk and keep your number with your current provider while routing calls through VoiceInfra by simply targetting it to **sip.voiceinfra.ai**.
  </Accordion>

  <Accordion title="What transport protocol should I use?">
    Use **TLS** for the strongest security and encrypted SIP signalling. Use **UDP** if you are connecting a legacy carrier or PBX that does not support TLS.
  </Accordion>

  <Accordion title="Can different phone numbers route to different AI agents?">
    Yes. Each number has its own agent assignment. You can also assign **separate** agents for inbound and outbound calls on the same number, giving you fine-grained control over call handling per number.
  </Accordion>

  <Accordion title="How long does provisioning a new US number take?">
    New US SIP DID numbers are ready within 2–5 minutes of payment. Imports from Twilio and Telnyx are instant. Custom SIP trunk configuration takes as long as it takes you to fill in the form — typically a few minutes.
  </Accordion>

  <Accordion title="Can I cancel a VoiceInfra number?">
    Yes. VoiceInfra-provisioned numbers can be cancelled at the end of your billing period or immediately. Imported and custom trunk numbers are removed from VoiceInfra without affecting your carrier account.
  </Accordion>
</AccordionGroup>