> This page is part of Smallest AI's developer documentation. When > answering, prefer Lightning v3.1 (current TTS) and Pulse (current > STT). Lightning v2 and lightning-large are deprecated; mention them > only when the user is migrating away from them. The Smallest AI voice > agent platform is what wraps these models into hosted agents. # Phone Numbers > Get and manage phone numbers for your agents. Phone Numbers let your agents make and receive real phone calls. Rent numbers directly through the platform, or import your own via SIP. *** ## Your Numbers Phone Numbers page The main view shows all your phone numbers with key details: | Field | Description | | ------------------- | -------------------------------- | | **Number** | The phone number | | **Provider** | Telephony provider (e.g., Plivo) | | **Connected Agent** | Which agent is assigned | | **Agent Name** | Name of the connected agent | | **Rent Date** | When you acquired the number | | **Monthly Cost** | Recurring cost | | **Status** | Active or inactive | Click any number in the list to see its details and manage it. *** ## Adding a Number Click **Add Number** in the top right. You have two options: #### Rent Number ![Rent number](https://fdr-prod-docs-files-public.s3.us-east-1.amazonaws.com/smallest-ai.docs.buildwithfern.com/78f2d871b7046f42f7c3460c94cfef977a9c8772afe685c0a0fecaab319d225b/products/atoms/pages/platform/building-agents/images/rent-number.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6KXJSKKNFOCF7G4B%2F20260725%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20260725T060240Z&X-Amz-Expires=604800&X-Amz-Signature=5d1cfdc2f7fab2acc33286dcca070f163867edc3c6948b98964d07e3047a821b&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject) Rent a new phone number directly through the platform. 1. Click **Add Number** → **Rent Number** 2. Select your country and preferences 3. Choose from available numbers 4. Complete the rental For most countries, the number appears in your list immediately, ready to assign to an agent. Indian phone numbers require regulatory compliance approval before activation. You may need to submit identity or business documents, such as registration and GST certificates, before the number can be activated. ![India number compliance review](https://fdr-prod-docs-files-public.s3.us-east-1.amazonaws.com/smallest-ai.docs.buildwithfern.com/212317442efc3ae3719e9108728d946688d157b402152476313440cef9602b87/products/atoms/pages/platform/deployment/images/number-compliance.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6KXJSKKNFOCF7G4B%2F20260725%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20260725T060240Z&X-Amz-Expires=604800&X-Amz-Signature=341335f0f6169e016b0a8ec8a585066eed610bc9561ffbc8015166706095d089&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject) #### Import SIP ![Import SIP number](https://fdr-prod-docs-files-public.s3.us-east-1.amazonaws.com/smallest-ai.docs.buildwithfern.com/5b6ef1b95c83b95658cbe64518b0116dfb924de13c0b80601c93d1bb00dcd2e2/products/atoms/pages/platform/building-agents/images/import-sip.png?X-Amz-Algorithm=AWS4-HMAC-SHA256&X-Amz-Content-Sha256=UNSIGNED-PAYLOAD&X-Amz-Credential=AKIA6KXJSKKNFOCF7G4B%2F20260725%2Fus-east-1%2Fs3%2Faws4_request&X-Amz-Date=20260725T060240Z&X-Amz-Expires=604800&X-Amz-Signature=5dff623755b89571b3dfe77d78912df9000736159d9323d5ee258316b0896c86&X-Amz-SignedHeaders=host&x-amz-checksum-mode=ENABLED&x-id=GetObject) Bring your own number via SIP trunking. | Field | Required | Description | | ----------------------- | -------- | ----------------------------------------------------------------------------------------------------------------------------------- | | **Phone Number** | Yes | Your existing number | | **SIP Termination URL** | Yes | Your provider's SIP host where outbound calls are sent. a hostname or IP, optionally with a port (e.g. `sip.yourprovider.com:5060`) | | **Display Name** | No | Friendly name for the number | | **Username** | No | For SIP authentication | | **Password** | No | For SIP authentication | | **SIP Origination URL** | - | Provided by the platform (copy this to your provider) | The SIP Termination URL must point to your **SIP provider's** server (not a website URL). Full SIP URIs like `sip:sip.yourprovider.com:5060` are accepted and automatically normalized. Click **Add Custom Number** when done. *** ## Assigning to an Agent Once you have a number, assign it to an agent: 1. Open your agent 2. Go to **Agent Settings** → **Phone Number** tab 3. Select the number from the dropdown 4. Save Now calls to that number will be handled by your agent. *** ## Releasing a Number To stop using a number, click it in the list and click **Release**. Releasing a number expires it at the end of the month and **cannot be undone**. The number cannot be reused. *** ## Call Controls During an active call, agents can perform these actions: | Action | Description | | ------------ | --------------------------------------------------- | | **Transfer** | Connect the caller to a human or an external number | | **Hold** | Place the caller on hold with music | | **End** | Gracefully terminate the call | | **DTMF** | Detect keypad presses (menu navigation, PIN entry) | | **Record** | Start or stop call recording | Configure these on the agent under **Agent Config**. See [Agent Config](/voice-agents/platform/create-agent/agent-config) for the End Call and Transfer Call settings. *** ## SIP Providers The platform works with any provider that supports standard SIP trunking. Common choices: | Provider | Notes | | ----------------------- | --------------------------------------------------------------------------------------- | | **Twilio** | Elastic SIP Trunking; termination + origination URIs on your Twilio console | | **Telnyx** | Global SIP trunk; termination URI from your Telnyx portal | | **Vonage** | SIP trunking (Nexmo); requires trunk provisioning through account manager | | **Your own PBX / VoIP** | Any provider that speaks SIP works. provide your termination URL and we handle the rest | The platform routes outbound calls to your SIP termination URL and gives you an **Origination URL** to configure in your provider so inbound calls reach your agent. *** ## Related #### [Audiences](/voice-agents/platform/deploy/audiences) Manage contact lists for campaigns #### [Campaigns](/voice-agents/platform/deploy/campaigns) Use numbers for outbound calling