Bring Your Own Telephony

Overview

Bring your own telephony (BYO) lets you keep the phone numbers and the carrier contract you already have, and use them with a CallMissed AI voice agent. Nothing is ported, and you do not rent a number from us.

A connection has two halves, and calls only work once both are done:

1. You give CallMissed your provider credentials. We verify them against your provider, store them encrypted, and provision the trunk that carries audio between your provider and our voice agents.
2. You point the number's call routing at CallMissed. Inbound calls have to arrive at us, so the routing on the number (or on the trunk it belongs to) is switched over to the SIP endpoint we show you after connecting.

1. 1

   Connect the provider

   Paste your provider credentials into CallMissed; we verify them before storing

2. 2

   Provision the trunk

   CallMissed creates the SIP trunk on both sides and hands you the inbound SIP endpoint

3. 3

   Import numbers

   Your voice-capable numbers are read from your account and imported

4. 4

   Route and answer

   Point the number's call routing at CallMissed and assign a voice-agent bot

Prerequisites

• An active account with a supported telephony provider, holding at least one voice-capable number.
• Admin access to that provider's dashboard, enough to create or edit a trunk and change a number's call routing.
• A CallMissed account with the owner or admin role.

Note: Numbers you bring keep their existing contract and billing with your provider. CallMissed does not charge you a monthly number rental for them, unlike numbers you rent from us through the Telephony API.

Rent from us, or bring your own

Both paths converge: once a number is in CallMissed, whether rented or imported, you assign a bot and configure the call the same way.

Supported providers

What the Status column means:

• Self-serve: you can connect it yourself from the dashboard, start to finish. The three self-serve providers are documented below.
• Set up by our team: the integration exists, but part of the trunk mapping has to be arranged with the provider on your behalf. Write to support@callmissed.com with your account details and we complete the connection with you.
• Contact us: not wired yet. Tell us which provider you are on at support@callmissed.com and we will scope it.

Over the API, a provider that is not self-serve returns 501 when you try to connect it.

Do not follow the self-serve steps for a "Set up by our team" provider. Their trunk mapping is done by the provider's own support team, not from your console, and a half-configured trunk silently drops inbound calls.

Twilio

Connects as an Elastic SIP Trunk in your own Twilio account.

Inbound calls on a Twilio trunk are matched on the called number, not on a SIP password. A number that is not imported, or that is still routed by its own voice webhook in the Twilio Console, will not reach your agent even though the credentials are valid.

Plivo (your own account)

Connects as a Zentrunk SIP trunk in your own Plivo account. This is the BYO path. It is separate from numbers you rent from CallMissed, which are billed as rentals.

Custom SIP

Use this for any provider not listed above that can terminate a SIP trunk. You supply the trunk details yourself, and you enter the numbers manually because there is no account API for us to read them from.

Fields you supply

Outbound calls authenticate with the SIP username and password, not with an IP allowlist. We cannot guarantee a static egress IP for allowlisting, so an IP-only trunk cannot be authorised. Ask your provider to enable digest (username and password) authentication on the trunk. If they cannot, write to support@callmissed.com before you start.

Inbound. Set CallMissed's SIP host as the inbound destination on your provider's trunk, then confirm each number is attached to that trunk on their side. The connection response does not include that host for Custom SIP, so ask support@callmissed.com for it. Only the numbers you entered are accepted.

Connecting in the dashboard

The wizard is the same for every self-serve provider.

A connection is saved only once verification and provisioning have both succeeded, so a new connection is active straight away. If either step fails, the request returns the reason and nothing is saved; fix the cause at your provider and connect again. A connection you no longer want is disconnected (deleted).

After connecting

• Imported numbers appear alongside rented ones. They show up on the Phone numbers page and in the number list of the Telephony API, tagged with the provider they came from.
• Assign an agent the same way. Link a voice-agent bot to the number exactly as you would for a rented number. See Voice Calling for building the bot.
• Per-number call settings still apply. Greeting, language, voice, STT and TTS models, system prompt, tools, and maximum call duration are all set per number and override the linked bot on that number's calls. The full list is in Per-number call overrides.
• Disconnecting only affects CallMissed. Removing a provider connection removes the trunk CallMissed set up for it, so calls on its numbers stop reaching your agent. The imported numbers stay in your number list, detached from any connection. Nothing is released or cancelled at your provider, and your contract with them is unchanged. Point the number's routing back at your own application before you disconnect, or inbound calls will go nowhere.

API reference

Everything the dashboard wizard does is also available with your cm_ key. Base path: https://api.callmissed.com/api/v1/telephony. Reads need telephony:read; connecting, disconnecting and importing need telephony:write (and an owner/admin role when called with a JWT).

The provider catalogue

GET /provider-catalog returns one entry per provider: id, label, description, integration (sip, wss or manual), can_auto_provision, can_list_numbers, contact_us (true means it cannot be connected over the API), credentials (the fields to send — each with name, label, type, required, help) and docs_url.

Connect a provider

curl -X POST https://api.callmissed.com/api/v1/telephony/provider-connections \
  -H "Authorization: Bearer cm_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{
    "provider": "twilio",
    "label": "Twilio, prod account",
    "credentials": {"account_sid": "ACxxxxxxxx...", "auth_token": "your_twilio_auth_token"}
  }'

Response (201 Created) — the connection:

{
  "id": "4b8d2f10-6c3e-4a1b-9f2d-7e8a9b0c1d2e",
  "tenant_id": "1a2b3c4d-5e6f-7a8b-9c0d-1e2f3a4b5c6d",
  "provider": "twilio",
  "label": "Twilio, prod account",
  "status": "active",
  "external_account_id": "ACxxxxxxxx...",
  "provider_trunk_id": "TKxxxxxxxx...",
  "config": {"outbound_address": "example.pstn.twilio.com", "transport": "tcp"},
  "last_error": null,
  "has_credentials": true,
  "created_at": "2026-09-20T09:00:00Z",
  "updated_at": "2026-09-20T09:00:00Z"
}

The response also carries internal routing identifiers for the trunk; treat any field not shown here as opaque. Credentials are never returned.

List and import numbers

GET /provider-connections/{connection_id}/numbers returns the numbers on your provider account (for Custom SIP, the ones you entered): e164, provider_number_id, number_type, voice_enabled, sms_enabled, label, already_attached (the provider already routes it somewhere else — importing takes it over) and already_imported (it is already on your CallMissed account).

curl -X POST https://api.callmissed.com/api/v1/telephony/provider-connections/{connection_id}/import \
  -H "Authorization: Bearer cm_your_api_key" \
  -H "Content-Type: application/json" \
  -d '{"numbers": ["+14155550123", "+14155550124"]}'

numbers takes 1–50 +E.164 entries; duplicates are collapsed. The response is the imported numbers, in the same shape as GET /numbers on the Telephony API, with no rental charge. 409 if the connection is not active or a number is already in use (your own clashes are named; a number held elsewhere is only counted). A number that cannot be attached to the trunk at your provider is still imported and works for outbound calls; attach it on the provider's side for inbound.

Disconnect

curl -X DELETE https://api.callmissed.com/api/v1/telephony/provider-connections/{connection_id} \
  -H "Authorization: Bearer cm_your_api_key"

204 No Content. See After connecting for what this does and does not change.

Security

• Credentials are encrypted at rest before they reach the database. They are decrypted only in memory, only when a call to your provider needs them.
• They are never returned by the API. No response body, log line, or webhook payload contains a provider secret. A connection exposes only whether credentials are present (has_credentials), your provider account id (Account SID or Auth ID — an identifier, not a secret), and the non-secret connection facts (trunk ids, SIP address, transport).
• Scoped per tenant. A connection belongs to one tenant and is only ever readable inside it.
• To rotate a credential, change it at your provider, then connect the provider again in CallMissed with the new pair. Verification runs against the new credential before it replaces the old one.

If you believe a credential has leaked, revoke it at your provider first, then reconnect. Revoking at the provider takes effect immediately, whatever is stored on our side.

Troubleshooting

Still stuck, or on a provider marked Set up by our team? Write to support@callmissed.com with your provider, the connection label, and the number you are testing.