Numbers And BYOC

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Overview

Phone numbers are the bridge between your AI agents and real phone calls. In Callin.io, you’ll manage this in two places:

• Numbers: Buy numbers through Callin.io, import from providers, or verify a personal number.
• BYOC (SIP Trunk): Bring your own carrier by connecting Telnyx or any SIP provider.

Use these shortcuts to jump straight into the app:

• Go to Numbers: Open Numbers
• Go to BYOC (SIP Trunk): Open BYOC

Tip: If you’re getting started quickly, buy a US/Canada number (instant). If you need an international number, be ready to submit documents (country rules vary).

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Numbers

The Numbers page shows every number connected to your workspace (purchased, imported, personal, Telnyx, or BYOC). From here, you can add new numbers and confirm each number’s status.

Screenshot: The Numbers page where you can filter by provider and click + Add Number to purchase or import numbers.

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What you can do in Numbers

When you click + Add Number, you’ll typically see these options (wording may vary slightly by account/plan):

• Purchase Number (buy through Callin.io)
• Import from Twilio
• Add Personal Number
• Add Telnyx Number (after Telnyx is connected)

You’ll also usually see filters like Purchased, Twilio, Personal, Telnyx, and BYOC (SIP Trunk) to quickly find what you’re looking for.

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Option A: Purchase a number through Callin.io

Buying numbers through Callin.io is the simplest way to get started.

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US & Canada: instant purchase

For United States and Canada, the purchase flow is typically instant:

1. Go to Open Numbers.
2. Click + Add Number → Purchase Number.
3. Choose the Country.
4. Choose a type:
   • Local
   • Toll-Free (if available)
5. (Optional) Use Search by Area Code (example: 415).
6. Click Search Numbers.
7. Select a number from the list.
8. Click Purchase Selected Number.

Important: After purchase, the number should appear in your list. If you see a warning like “this number is not assigned to any agent,” you still need to assign it to an agent before using it.

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Other countries: request + documentation

For many non-US/Canada countries, purchasing is a request-based flow:

• You select the country and number type (for example Local or Mobile).
• You may see Request Type options such as New number and Porting.
• You must provide required information and upload documents.
• You submit the request, pay any required fees, and then the request is reviewed.

You can typically track these under a tab like Number Requests.

Common document requirements (examples)

Exact requirements depend on the country and number type, but you may be asked for items like:

Tip: In the request form, some fields may have their own Save button and show Pending until you save/upload successfully.

Fees + review

Some countries show a fee payment step (for example, a one-time activation fee and a monthly cost). After you submit and pay:

• You’ll receive a Request ID
• The request is reviewed by an operator
• Once approved, the number appears in your Numbers list

Important: Approval timing can vary by country and provider rules. If you’re on a deadline, start the request early.

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Option B: Import numbers from Twilio

If you already own numbers in Twilio, you can import them into Callin.io:

1. Go to Open Numbers.
2. Click + Add Number → Import from Twilio.
3. Enter your Twilio Account SID and Twilio Auth Token.
4. Click Search Twilio Numbers and select the numbers to import.
5. Assign imported numbers to an AI agent when you’re ready to use them.

Common mistake: Copying the wrong Twilio credentials (for example, using a test credential instead of live). If no numbers appear, re-check your Twilio project and permissions.

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Option C: Add a Personal Number (outbound-only)

A Personal Number is useful when you want to place outbound calls from your own phone number—but it cannot receive inbound calls inside Callin.io.

Screenshot: The Add Personal Number modal with phone input and the verification process (you receive a verification call and enter the code).

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Verify your personal number

1. Go to Open Numbers.
2. Click + Add Number → Add Personal Number.
3. Select your country code and enter your phone number.
4. Click Verify Number.
5. You’ll receive a verification call.
6. Enter the verification code when prompted.
7. After verification, the number is added to your account.

Important: Personal numbers are outbound-only. If you need inbound calls, use a purchased/imported number or BYOC.

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Option D: Add/Import Telnyx numbers

If your Telnyx account is connected (via BYOC), you can import active Telnyx numbers into Callin.io:

1. Go to Open Numbers.
2. Click + Add Number → Add Telnyx Number.
3. Select the Telnyx numbers you want to add/import.
4. Confirm, then assign them to agents as needed.

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Assign numbers to agents (so they can be used)

Buying or importing a number is only step one—your agent still needs to use it. On the Numbers list, if you see a warning like “not assigned to any agent,” assign the number to the right AI agent before going live.

Tip: Keep one “test” number separate from production while you’re iterating on prompts and call flows.

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BYOC (SIP Trunk)

BYOC means Bring Your Own Carrier. Instead of buying numbers through Callin.io, you connect your own telephony provider using a SIP trunk. Typical reasons to use BYOC:

• You already have a carrier contract (enterprise telephony)
• You need custom routing, SBC control, or compliance constraints
• You want to avoid Callin-managed telephony rules by using your own provider

Go here to set it up: Open BYOC

Screenshot: BYOC setup where you can connect Telnyx and synchronize numbers into Callin.io.

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What is a SIP Trunk (simple explanation)

A SIP trunk is a connection between a phone carrier and your calling system. Think of it like a “phone line over the internet” that can handle inbound/outbound calls—often used by businesses.

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Option 1: Connect Telnyx

If you use Telnyx, Callin.io can guide the setup with an API key:

1. Go to Open BYOC.
2. Select the Telnyx tab.
3. Paste your Telnyx API Key.
4. Click Start.

During setup, you’ll typically see steps like:

• Saving the Telnyx API key
• Fetching active Telnyx numbers (DIDs)
• Storing numbers in your Callin.io account
• Provisioning the SIP trunk (inbound + outbound)
• Creating provider phone numbers

Once it completes, your Telnyx numbers should appear under Numbers.

Important: If your Telnyx key doesn’t have permission to read numbers/DIDs, Callin.io won’t be able to fetch them.

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Option 2: Connect another SIP provider (Generic SIP Trunk)

If your provider is not Telnyx, use the Other SIP Provider tab. You’ll typically configure three areas: Basic, Inbound, and Outbound.

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Basic

• Label: A friendly name (example: “HQ SIP Trunk”)
• Phone Number (E.164): Full international format (example: +15551234567)
• You may also see toggles like Supports inbound and Supports outbound

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Inbound

Inbound calls go from the carrier to your system.

• Inbound SBC / FQDN: Your SIP address (example: sip.example.com:5061)
• Transport: Often TLS or UDP
• Media encryption: Enable if your provider supports it

Tip: Inbound often does not require credentials. Many carriers authenticate inbound calls by IP allowlists or trunk configuration.

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Outbound

Outbound calls go from Callin.io to your carrier.

• Outbound SBC / FQDN: Your provider’s SIP server
• Transport and Media encryption
• Username and Password: Your SIP credentials
• Allowed countries (outbound): Often Worldwide or a Custom list

When finished, click Save & Import.

Common mistake: Using the wrong SBC/FQDN or credentials. If outbound calls fail, re-check your SIP username/password and whether your provider requires a specific port or transport.

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Minutes and billing (what to expect)

Billing can have two parts: Callin usage and telephony carrier charges. What you see depends on how you connect numbers.

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Callin compute minutes

Compute minutes represent the time your AI agent is active (listening, processing, responding). This is the core usage metric for AI calling.

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Callin-managed telephony: important billing notice (first-minute billing)

When you place calls using Callin-managed telephony (for example, numbers purchased through Callin.io and routed through Callin’s carrier), you may see a first-minute billing rule:

• Minimum charge is 1 minute
• After the first minute, billing typically follows the actual call duration
• This rule typically does not apply to:
  • Browser test calls
  • Imported own numbering (Telnyx or Twilio imports)
  • External SIP trunk (BYOC)

Important: The exact billing behavior can vary based on your setup and provider routing. If you want to avoid Callin-managed telephony rules, import your own numbers or use BYOC.

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Personal number billing reminder

Personal numbers are outbound-only, and calls made using a personal number can still fall under Callin-managed telephony rules depending on how your account routes calls.

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Troubleshooting

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“I can’t make calls”

• Check that you have at least one active number
• Make sure the number is assigned to an agent
• If using BYOC, confirm your SIP trunk settings are correct (SBC/FQDN, transport, credentials)

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“My personal number isn’t receiving inbound calls”

• That’s expected: Personal Numbers are outbound-only
• Use a purchased/imported number or BYOC for inbound calling

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“My imported numbers don’t show up”

• Re-check credentials (Twilio SID/Auth Token, Telnyx API Key)
• Confirm the numbers are active in the provider account
• Try again and verify you’re using the correct project/sub-account in the provider

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Final note

If you want the fastest setup, start with a US/Canada number purchased in Callin.io. If you need advanced routing or already have a carrier, connect BYOC. Once your number is added and assigned, your AI agents can place and receive real phone calls at scale.