--- title: Exotel SIP trunk API Reference for Voice AI slug: exotel-agentstream/exotel-sip-trunk-api-reference-for-voice-ai createdAt: 2026-04-01T14:22:16.204Z --- Use these snippets from the support articles for **ElevenLabs**, **LiveKit**, **Retell**, **Bolna**, **Pipecat (via Daily SIP)**, **Smallest AI (Atoms)**, **Vocallabs**, **Rapida AI**, and **NLPearl.AI** integrations. Replace placeholders; do not commit real secrets. **GitHub repo (reference):** https\://github.com/exotel/AgentStream-VoiceAIEcosystem | Placeholder | Description | | ---------------- | ------------------------------------------------------------------------------------------ | | Account Creation | [Exotel Indian Account](https://my.in.exotel.com) | | API\_KEY | Exotel API Key [(API Settings](https://my.in.exotel.com/apisettings/site#api-credentials)) | | API\_TOKEN | Exotel API Token | | ACCOUNT\_SID | Exotel Account SID | | SUBDOMAIN | api.in.exotel.com (India) or api.exotel.com (Singapore) | | TRUNK\_SID | Returned when you create a trunk (trunk\_sid in response) | **Authentication:** HTTP Basic — https\://API\_KEY\:API\_TOKEN\@SUBDOMAIN/... **Trunk API rate limit:** 200 requests per minute on these trunk configuration APIs (Exotel SIP API reference). **Outbound call rate (default):** Exotel typically allows **200 outbound call attempts per minute** by default (account-level). If you need a higher outbound initiation limit, contact your **CSM**. **Where to get API credentials:** API Settings (India) (or your cluster dashboard). **Headers:** Content-Type: application/json on POST/PUT. ### Exotel edge: IP and port Exotel documents **SIP signaling toward their gateway** using **edge IP addresses and ports** — for example **TLS on port 443** or **TCP on port 5070** — per Exotel network and firewall. Use the **IP\:port** (and transport) Exotel gives you in onboarding or support. Exotel may also share **edge hostnames** (instead of raw IPs). Common India examples you may see are: - **TCP:** in.voip.exotel.com:5070 - **TLS:** in.voip.exotel.com:443 Use the exact **host/IP + port + transport** Exotel assigns to your account/cluster. If a provider UI requires an **IPv4 literal** (no hostname), resolve the hostname to the IPv4 Exotel intends you to use (or request the explicit edge IPs from Exotel support). The **domain\_name** field in **Create trunk** is Exotel’s **account SIP domain** for the trunk record ({ACCOUNT\_SID}.pstn.exotel.com). That is separate from the **edge IP\:port** your Voice AI platform uses to send SIP to Exotel. ### Outbound trunk vs inbound SIP trunk | Flow | Exotel API steps | | ------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | | **Outbound SIP** (Voice AI → Exotel → PSTN) | **1.** Create trunk → **2.** Map DID → **3.** POST .../credentials (digest). **Optional:** POST .../whitelisted-ips **only** if the Voice AI provider gives you a **fixed static egress IP** to allow — see below. **Do not** use destination URI for this path unless Exotel instructs you otherwise. | | **Inbound SIP** (PSTN → Exotel → Voice AI) | After trunk + DID, **map destination URI** on the trunk to the partner’s SIP host/port/transport. Use **Flow → Connect** with **sip:\** in **Dial whom** (see support articles). | ### Trunk ACL (whitelisted-ips) Exotel trunk ACL is for **static IP allowlisting** from your Voice AI provider when they give you a **single fixed egress IP**. **Exotel does not support CIDR range whitelist on the trunk** — use **one IP per POST** with mask: 32. If the provider only offers non-static or range-based egress, use **digest credentials** and coordinate with Exotel on what is supported. ### Trunk ACL (whitelisted-ips) Exotel trunk ACL is for **static IP allowlisting** from your Voice AI provider when they give you a **single fixed egress IP**. **Exotel does not support CIDR range whitelist on the trunk** — use **one IP per POST** with mask: 32. If the provider only offers non-static or range-based egress, use **digest credentials** and coordinate with Exotel on what is supported. **Important (auth precedence):** Avoid mixing **IP allowlisting** and **digest auth** unless Exotel support has confirmed the expected behavior for your account. In some SIP deployments, once an **IP allowlist** is enabled, the platform may treat **source-IP** as the primary trust signal, and digest behavior can become confusing (especially if a provider publishes **shared / multi-tenant** egress ranges). If your provider only publishes **CIDR ranges** (no dedicated static /32 IPs), do **not** attempt to “whitelist the range” on Exotel — rely on **digest** and work with Exotel/provider support for the correct model. ### Recommendation :::BlockQuote Use Credential-based (Digest) Auth for SIP outbound trunk configuration with all Voice AI providers. IP-based whitelisting should not be used as the sole or primary authentication mechanism for these trunks. ::: ## Create trunk POST /v2/accounts/{ACCOUNT\_SID}/trunks ```curl curl -s -X POST "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks" \ -H "Content-Type: application/json" \ -d '{ "trunk_name": "my_trunk_name", "nso_code": "ANY-ANY", "domain_name": "'"${ACCOUNT_SID}"'.pstn.exotel.com" }' ``` trunk\_name: alphanumeric + underscores, max 16 characters. ## Map phone number (DID) to trunk POST /v2/accounts/{ACCOUNT\_SID}/trunks/{TRUNK\_SID}/phone-numbers ```curl curl -s -X POST "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/phone-numbers" \ -H "Content-Type: application/json" \ -d "{\"phone_number\": \"+9198XXXXXXXX\"}" ``` Optional: "mode": "flow" for StreamKit/Voice AI routing. Save the returned ID for updates. ## Create SIP digest credentials (outbound auth) POST /v2/accounts/{ACCOUNT\_SID}/trunks/{TRUNK\_SID}/credentials :::BlockQuote Use the **same** `user_name` and `password` on the Voice AI platform (ElevenLabs SIP digest, LiveKit authUsername / authPassword, Retell termination, etc.). ::: ```curl curl -s -X POST \ "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/credentials" \ -H "Content-Type: application/json" \ -d '{ "user_name": "SIP_USER", "password": "SIP_PASS", "friendly_name": "voice_ai_platform" }' ``` ## Whitelist IP (ACL) — static provider IP only POST /v2/accounts/{ACCOUNT\_SID}/trunks/{TRUNK\_SID}/whitelisted-ips Use **only** when your Voice AI provider gives a **single static egress IP** you must allow. **Repeat the call for each distinct static IP** (no CIDR ranges on trunk). ```curl curl -s -X POST "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/whitelisted-ips" \ -H "Content-Type: application/json" \ -d '{"ip": "203.0.113.50", "mask": 32}' ``` ## Set destination URI (inbound SIP — PSTN toward Voice AI partner) POST /v2/accounts/{ACCOUNT\_SID}/trunks/{TRUNK\_SID}/destination-uris Used for **inbound** routing: PSTN → Exotel → your SIP partner (FQDN or host/port/transport per partner docs). **Not** part of the minimal **outbound** SIP setup. ```curl curl -s -X POST "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/destination-uris" \ -H "Content-Type: application/json" \ -d '{ "destinations": [ { "destination": "partner.example.com:5061;transport=tls" } ] }' ``` ## Verify (GET) ```curl curl -s "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}" curl -s "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/phone-numbers" curl -s "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/whitelisted-ips" curl -s "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/destination-uris" ```