Twilio

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Prerequisites

• A Daily SIP trunk — note its sip_uri from the create call, for example sip:examplecorp-supporttwilio.siptrunk.sip-us.daily.co.
• A Twilio account with a phone number and Elastic SIP Trunking enabled.

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Configure the trunk

1

Create an Elastic SIP Trunk

In the Twilio Console, open Elastic SIP Trunking → Manage → Trunks and click Create new SIP Trunk. Give it a friendly name (for example examplecorp-support) and save. The trunk opens with a side menu of General, Termination, Origination, and Numbers.On General, Secure Trunking is supported — turn it on if you want encrypted signaling and media. Twilio enforces TLS signaling and SRTP media together under that one setting, and with it enabled “any non-encrypted calls will be rejected”, so you must point Origination at port 5061 with transport=tls in step 2. Leaving it off is fine too: the call then runs as plain SIP with unencrypted RTP. Either way, admission is handled by the IP allowlist in step 4.

2

Point Origination at Daily

Open Origination and, under Origination URIs, click Add new Origination URI. Fill in the Add Origination URL dialog:

• Origination SIP URI — your Daily sip_uri, host only: sip:examplecorp-supporttwilio.siptrunk.sip-us.daily.co. Leave the user part off and let Twilio populate it with the dialed number. Daily routes on the host label and ignores the user part entirely, so a custom user part buys you nothing — and it changes Twilio’s behaviour, moving the dialed number into a SIP Diversion header instead.
• Priority — prefilled 10; the range is 0–65535 and the lowest number is tried first.
• Weight — prefilled 10; the range is 1–65535, and a higher number takes more of the load between equal-priority URIs.
• Enabled — leave it enabled.

Click Add. The URI appears in the Origination URIs table with its priority, weight, and enabled tick.A trunk accepts up to ten Origination URIs; one is enough unless you want failover.To send signaling over TLS, append the transport parameter and use port 5061 — sip:examplecorp-supporttwilio.siptrunk.sip-us.daily.co:5061;transport=tls. Twilio defaults to UDP, and also supports transport=tcp. Daily accepts UDP and TCP on 5060 and TLS on 5061. If you enabled Secure Trunking in step 1, this TLS form is required rather than optional.

3

Attach your phone number

Open Numbers and use Add a number to attach the Twilio number that should route to Daily — the menu lets you pick an existing number or buy a new one. Attached numbers are listed with their friendly name and emergency-address status.

4

Secure the trunk

Add Twilio’s signaling IP ranges to the Daily trunk’s trunk_config.allowed_ips so it accepts calls from Twilio and nobody else — see Securing the trunk below.

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Securing the trunk

curl --request PUT \
  --url https://api.daily.co/v1/sip-trunk/$TRUNK_ID \
  --header 'Authorization: Bearer $DAILY_API_KEY' \
  --header 'Content-Type: application/json' \
  --data '{
    "trunk_config": {
      "allowed_ips": [
        "54.172.60.0/30",
        "54.244.51.0/30",
        "54.171.127.192/30",
        "35.156.191.128/30",
        "54.65.63.192/30",
        "54.169.127.128/30",
        "54.252.254.64/30",
        "177.71.206.192/30"
      ]
    }
  }'

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Pass caller context (optional)

"sipHeaders": { "X-Account-Id": "acct_42", "X-Department": "billing" }

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Test

{
  "event": "sip_trunk.incoming",
  "trunk": {
    "id": "6abf683d-dbcd-43a4-837d-e9317a34c0d6",
    "description": "my support sip trunk",
    "trunk_name": "supporttwilio"
  },
  "room": {
    "name": "uX9j9s9H1ii0VXhy5S1c",
    "url": "https://examplecorp.daily.co/uX9j9s9H1ii0VXhy5S1c",
    "exp": 1788366155
  },
  "call": {
    "sipCallIdHeader": "063ce834018bb00b9707efacb209cc42@0.0.0.0",
    "From": "sip:+15551234567@pstn.twilio.com:5060;isup-oli=00;pstn-params=9084810000",
    "To": "sip:+15550001111@examplecorp-supporttwilio.siptrunk.sip-us.daily.co",
    "requestUri": "sip:+15550001111@examplecorp-supporttwilio.siptrunk.sip-us.daily.co",
    "sourceIp": "54.172.60.2",
    "fromDomain": "pstn.twilio.com",
    "fromDisplayName": "+15551234567",
    "diversion": "<sip:+15550001111@twilio.com>;reason=unconditional",
    "pAssertedIdentity": "\"+15551234567\" <sip:+15551234567@206.147.72.106:5060>",
    "sipHeaders": {
      "X-Twilio-VerStat": "TN-Validation-Passed-A",
      "X-Twilio-AccountSid": "ACxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx",
      "X-Twilio-CallSid": "CAxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"
    }
  },
  "domain": "examplecorp",
  "timestamp": 1788362555722
}

• sourceIp falls inside 54.172.60.0/30, the North America Virginia range from the allowlist above — a quick way to confirm which edge served the call.
• Twilio attaches its own X-Twilio-* headers without any configuration: X-Twilio-CallSid correlates the Daily room back to a Twilio call record, and X-Twilio-VerStat carries the STIR/SHAKEN attestation result. Any headers you add yourself arrive alongside them.
• diversion is populated for a forwarded call, here with reason=unconditional.
• pAssertedIdentity keeps the quoting from the SIP header, so it arrives as "+15551234567" <sip:…> including the quote characters — it is the raw header value. fromDisplayName is unquoted, so you can show it to a user as-is.
• sipCallIdHeader is not a stable host-qualified id — Twilio’s carries @0.0.0.0. Treat it as an opaque string.

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Troubleshooting

• Call fails immediately, nothing reaches your webhook — the source IP isn’t in allowed_ips. Check which edge Twilio actually used against its published ranges, and remember the ranges are /30, not whole /24s.
• 404 from Daily — the Origination URI host doesn’t match a trunk. Re-copy the sip_uri from the API response rather than typing it.
• Secure Trunking is on and the call never arrives — Twilio rejects non-encrypted calls under that setting, so the Origination URI has to use :5061;transport=tls (see step 1). Turning Secure Trunking on while Origination still points at 5060/UDP is the usual cause.
• Call connects but there’s no audio — confirm Twilio offers a codec Daily negotiates. With Secure Trunking on, also confirm signaling is reaching Daily on 5061/TLS.