> ## Documentation Index > Fetch the complete documentation index at: https://docs.callers.ai/llms.txt > Use this file to discover all available pages before exploring further. # Phone numbers and caller ID > Add phone numbers from Callers, Twilio, Telnyx, WhatsApp, or SIP, assign them to agents, and choose which number each call comes from. Every voice or text agent needs at least one phone number. Outbound agents use it as the caller ID; inbound agents answer calls and messages sent to it. The **Phone Numbers** page lists every number available to your account, where it comes from, and which agents use it. > [!NOTE] > > The **Phone Numbers** page is available to admins. ## Where numbers come from Numbers are grouped on the page by source: | Source | Shown as | Voice | Text | | :- | :- | :-: | :-: | | Numbers bought in Callers | **Managed by Callers** | ✓ | | | Your Twilio account | **TWILIO** (with the account name) | ✓ | ✓ | | Your Telnyx account | **TELNYX** | | ✓ | | Your WhatsApp Business account (360dialog) | **WHATSAPP** | | ✓ | | Your SIP trunk | **SIP - *connection name*** | ✓ | | | Numbers added by hand | **Manually Added** | ✓ | | Each number shows its country flag, location, and a tag when it's limited to one direction: **Only Outgoing**, **Only Incoming**, or **Only SMS**. Hover over a number to see which agents use it. ![Phone numbers page with a Managed by Callers section, a Twilio section with a Refresh link and SPAM tags on two numbers, and a SIP section with Add SIP Numbers and Delete All SIP Numbers actions](https://mintcdn.com/voxiaai/UGuY0UNIphM-6pUX/images/documentation/contacts/phone-numbers-page.png?fit=max\&auto=format\&n=UGuY0UNIphM-6pUX\&q=85\&s=474d66635830731fc00633d004674ea5) The Phone numbers page grouped by source, with the Check Spam button at the top. ## Add numbers **Buy a number** Click **Buy** at the top of the page, then **Buy number** to confirm. A US local number is added to your account. It supports both incoming and outbound calls. If you don't see **Buy**, buying numbers isn't available for your account yet. Contact [support@callers.ai](mailto:support@callers.ai). **Twilio** Click **Connect Twilio** and enter your Twilio **Account SID** and **Auth Token**. Your Twilio numbers appear under **TWILIO**. Numbers sync each time you open the page. If you just bought a number in Twilio and don't see it, click **Refresh** in the Twilio section. See [Twilio](https://docs.callers.ai/documentation/integrations/twilio.md) for setup details. **Telnyx** Connect Telnyx as described in [Telnyx SMS](https://docs.callers.ai/documentation/text-agents/telnyx-sms.md). Your numbers appear under **TELNYX** and sync each time you open the page. Click **Refresh** to sync on demand. Telnyx numbers are used for text agents. **WhatsApp** Connect your WhatsApp Business account as described in [WhatsApp](https://docs.callers.ai/documentation/text-agents/whatsapp.md). Click **Sync** in the WhatsApp section to pull in new numbers. **SIP** Connect your SIP trunk first. See [SIP trunking](https://docs.callers.ai/documentation/integrations/sip.md). Then click **Add SIP Numbers** in the connection's section, paste your numbers, and click **Done**. Use **Test SIP** to place a test call through the trunk. To remove SIP numbers, select them and click **Delete N SIP Numbers**, or click **Delete All SIP Numbers** with nothing selected. Deleted numbers are disconnected from any agent that uses them. ## Assign numbers to an agent **1. Open the agent's channels** Open the agent, click **Edit**, open the [general settings](https://docs.callers.ai/documentation/build-your-agent/agent-setup.md#channels), and select the **Voice Channels** card (**Text Channels** for text agents). **2. Select numbers** Under **Phone numbers**, search and tick the numbers this agent should use. Select several numbers to spread outbound calls across them. **3. Choose a dialing strategy** With more than one number selected on an outbound agent, choose a **Dialing Strategy** (see below). An incoming number can belong to only one agent at a time, so calls always reach a single agent. A number that's already taken shows "This phone number is already accepting calls on another Agent" and can't be selected. ## Dialing strategies When an outbound agent has several numbers, the dialing strategy decides which one each call comes from. | Strategy | How it picks a number | | :- | :- | | **Rotate Numbers** (default) | Spreads calls across your number pool, so each number carries a similar share of calls. Helps avoid spam flags. | | **Prefer Local Numbers** | Uses numbers that match the contact's location (country, then region and city) when you have one. Rotates between matching numbers. Falls back to the whole pool when none match. | | **Auto Optimize** | Designed to favor the numbers with the best pickup rates by area code and time of day. It currently rotates numbers the same way as **Rotate Numbers**. | > [!TIP] > > People are more likely to answer a local number. If you call across many US area codes, add numbers in your busiest area codes and choose **Prefer Local Numbers**. ## Local dialing Turn on **Local Dialing** under the agent's **Technical Settings** to dial contacts in local number format. Contacts can then be added without a country code, and any non-empty number is accepted at import. Use it when your SIP carrier expects national-format numbers. > [!NOTE] > > This feature is enabled per account. Contact [support@callers.ai](mailto:support@callers.ai) to turn it on. ## Spam checks Carriers and call-blocking apps can label a number as spam, which sends calls to voicemail or blocks them and lowers your answer rate. For more ways to raise pickup, see [Improve answer rates](https://docs.callers.ai/documentation/best-practices/improve-answer-rates.md). * **Check one number:** click **Check Spam**, enter an international phone number, and click **Check for Spam**. The result is either **Spam Risk Detected** or **No Spam Detected**. * **Automatic checks:** Callers checks your numbers in the background, starting with the ones agents actively use. Flagged numbers show a **SPAM** badge on the Phone Numbers page. * **Notifications:** when a number used by an agent is newly flagged, you get a notification naming the number and the agent. When a number is flagged, remove it from your agents and replace it with a fresh number. Spreading calls across more numbers with **Rotate Numbers** lowers the chance of flags. > [!NOTE] > > This feature is enabled per account. Contact [support@callers.ai](mailto:support@callers.ai) to turn it on. ## Duplicate contacts per number By default, each phone number can appear only once in an agent's contacts; importing it again updates the existing contact. Turn on **Allow Duplicate Phone Numbers** under **Technical Settings** to keep several contacts with the same number, for example several people reached through one office line. > [!WARNING] > > Once **Allow Duplicate Phone Numbers** is turned on, it can't be turned off for that agent. ## Remove a number You can delete numbers that are **Managed by Callers** and SIP numbers from the Phone Numbers page. If agents use the number, you'll see which ones and can click **Disconnect All** to remove it from them first. Twilio, Telnyx, and WhatsApp numbers are managed in those providers' own consoles. ## Troubleshooting > **A new Twilio or Telnyx number doesn't appear** > > Click **Refresh** in that provider's section. New numbers can take a moment to sync. > **I can't select a number for my inbound agent** > > The number already answers calls for another agent. Remove it from that agent first. > **The Dialing Strategy option isn't shown** > > It appears only on outbound agents with more than one number selected. > **My answer rate dropped suddenly** > > Check for **SPAM** badges on your numbers. Replace flagged numbers and spread calls across more numbers. ## Related > **[Telephony](https://docs.callers.ai/documentation/integrations/telephony.md)** > > Connect your own carrier or SIP trunk. > **[Scheduling and retries](https://docs.callers.ai/documentation/contacts/scheduling-and-retries.md)** > > Control when and how often contacts are dialed. > **[Do Not Call list](https://docs.callers.ai/documentation/contacts/do-not-call.md)** > > Block numbers that must not be called. > **[Notifications](https://docs.callers.ai/documentation/account/notifications.md)** > > Get alerts when a number is flagged. This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.