--- title: Connect Exotel SIP Trunk to ElevenAgents by ElevenLabs slug: exotel-agentstream/connect-exotel-sip-trunk-to-elevenagents-by-elevenlabs createdAt: 2026-04-01T16:08:31.890Z --- This guide explains how to connect **Exotel SIP trunking** to **ElevenAgents by ElevenLabs** so you can place and receive PSTN calls in India through Exotel while your agent runs on ElevenLabs. **GitHub repo (reference):** https\://github.com/exotel/AgentStream-VoiceAIEcosystem ## What you will set up | Integration | Direction | When to use | | ------------------------- | ------------------------------ | ------------------------------------------------------- | | **Outbound SIP (digest)** | ElevenLabs → Exotel → PSTN | Agent **places outbound** calls via your Exotel DID | | **Inbound SIP** | PSTN → Exotel DID → ElevenLabs | Callers **dial** your Exotel number and reach the agent | **Separate the API work:** **Outbound SIP** uses only **create trunk → map DID → credentials**. **Inbound SIP** adds **destination URI** on the trunk (and Flow). **Trunk ACL** (whitelisted-ips) applies **only** when your Voice AI provider gives you a **static egress IP** — Exotel trunk **does not support CIDR range** allowlisting; use **one static IP per API call** (mask: 32) if needed. ## Architecture ### Outbound SIP (digest) :::BlockQuote ElevenLabs → SIP digest → Exotel edge IP\:port → Indian PSTN → Customer ::: ### Inbound SIP :::BlockQuote Customer → PSTN → Exotel DID → Flow (Connect) → sip:\ → … → sip.rtc.elevenlabs.io → ElevenLabs Agent ::: **Destination URI** on the trunk defines where Exotel sends **inbound** SIP toward ElevenLabs. In the **Connect** applet **Dial whom**, use **sip:\** only — the **trunk\_sid** string returned from **Create trunk** (not a full sip\:user\@host URI). For FQDN-only inbound (no digest on trunk), **do not** add POST .../credentials unless Exotel requires it for your design. ## Prerequisites ### Exotel - my.in.exotel.com with **SIP trunking** enabled. - **KYC**; Exophone (DID) in **E.164** (+91…). - **API Key**, **API Token**, **Account SID** from API credentials. - APIs: **https\://api.in.exotel.com** (India). ### ElevenLabs - Agents / Conversational AI and **SIP** phone import. - **Published agent**; **API key** if testing outbound via HTTP API. ### Network - SIP: **TCP** or **TLS**; RTP: **UDP** per Exotel network doc. ## Part A — ElevenLabs (dashboard) ### Outbound SIP (digest) 1. **Agents** → create/publish agent. 2. **Phone Numbers** → **Import a phone number from SIP trunk**. 3. **E.164** Exotel DID; **Transport** TCP/TLS per Exotel; **SIP digest** = same values you will set in Exotel POST .../credentials. 4. **Outbound address** = **Exotel edge IP\:port** from Exotel. 5. Import → **assign** number to agent. Note **agent\_phone\_number\_id** for API tests. ### Inbound SIP (ACL path) 1. Import number; leave digest **empty** if using ACL on ElevenLabs. 2. Allowlist **Exotel signaling IPs** on ElevenLabs if required (Exotel network doc). ## Part B — Exotel console - Numbers, KYC, App Bazaar / Flows for **Connect** when using inbound. ## Part C — Exotel APIs **Auth:** https\://API\_KEY\:API\_TOKEN\@api.in.exotel.com/... **Rate limit:** **200 requests/minute**. Templates: \_exotel-trunk-api-snippets.md. ### Outbound SIP — required steps only 1. **Create trunk** 2. **Map DID** to trunk 3. **POST .../credentials** — digest; must match ElevenLabs import **Optional (only if ElevenLabs gives a static egress IP):** POST .../whitelisted-ips with that **single IP**, mask: 32. Repeat per static IP if Exotel and your provider agree. **Do not** assume CIDR range whitelist on trunk. ```curl curl -s -X POST \ "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/credentials" \ -H "Content-Type: application/json" \ -d '{ "user_name": "SIP_USER", "password": "SIP_PASS", "friendly_name": "eleven_labs" }' ``` :::BlockQuote **Applicability:** **UI-driven** (ElevenLabs console for agents + phone numbers) with optional **API-driven** outbound triggering. ::: :::BlockQuote **Exotel edge:** Exotel provides **SIP edge IP address(es) and port(s)** for signaling (for example **TLS 443** or **TCP 5070** per Exotel network and firewall). Configure **\:\** in ElevenLabs — use the values Exotel assigns for your account. ::: :::BlockQuote **Edge hostnames you may see (India):** in.voip.exotel.com:5070 (TCP) and in.voip.exotel.com:443 (TLS). Use the exact host/IP + port + transport Exotel assigns. See \_exotel-trunk-api-snippets.md for details. ::: :::BlockQuote **ACL vs digest (important):** Avoid trying to whitelist **CIDR ranges**. Exotel trunk ACL is intended for **static /32 IPs** only (mask: 32). If a provider publishes only **CIDR** / shared egress ranges, prefer **digest** and coordinate with Exotel/provider support—mixing allowlists and digest can cause auth/routing issues in multi-tenant egress setups. ::: ### Inbound SIP — destination URI on trunk Map **inbound** SIP toward ElevenLabs (host/port/transport per ElevenLabs): ```curl curl -s -X POST "https://${API_KEY}:${API_TOKEN}@${SUBDOMAIN}/v2/accounts/${ACCOUNT_SID}/trunks/${TRUNK_SID}/destination-uris" \ -H "Content-Type: application/json" \ -d '{ "destinations": [ { "destination": "sip.rtc.elevenlabs.io:5060;transport=tcp" } ] }' ``` ### Connect applet (inbound) 1. App Bazaar → Flow → **Connect** applet. 2. **Dial whom:** **sip:\** — paste the **trunk\_sid** from the create-trunk API response (prefix sip: only; **not** a full SIP URI). 3. Map the Exophone to this Flow. Overview: Exotel Voice AI / SIP trunking. ## Test calls ### Lab validation (outbound) Outbound SIP has been **tested** end-to-end when trunk + DID + digest + (optional) static-IP ACL align. A **connected call** does not guarantee the **agent speaks** — see below. ### Outbound API Use ElevenAgents by ElevenLabs** outbound call** API — confirm the current URL in ElevenLabs API docs (paths change over time). ```curl curl -s -X POST "https://api.elevenlabs.io/v1/convai/" \ -H "xi-api-key: ${ELEVENLABS_API_KEY}" \ -H "Content-Type: application/json" \ -d '{ "agent_id": "YOUR_AGENT_ID", "agent_phone_number_id": "YOUR_PHONE_NUMBER_ID", "to_number": "+91XXXXXXXXXX" }' ``` ### Inbound Dial your Exotel DID; agent should answer via ElevenLabs. ### Call connects but agent does not speak (no bot audio) This section applies when the **call is triggered** but the **agent does not play** audio. | Check | Action | | ---------- | -------------------------------------------------------- | | Assignment | Imported DID **assigned** to the agent used in the API | | IDs | agent\_phone\_number\_id matches the imported SIP number | | Agent | Published; first message / voice configured | | Logs | ElevenLabs ConvAI traces for session errors | | RTP | If total silence, check UDP/RTP per Exotel network doc | ## Troubleshooting | Symptom | Likely cause | | ---------------------------- | ----------------------------------------------------------- | | SIP **401** | Digest mismatch (Exotel /credentials vs ElevenLabs) | | SIP **403** inbound | ElevenLabs ACL vs Exotel source IPs | | **408** / timeout | DNS/firewall to ElevenLabs FQDN | | Connect does nothing | **Dial whom** must be **sip:\**, not a full URI | | **Call triggers, no speech** | See Call connects but agent does not speak (no bot audio) | ## Official references | Resource | URL | | ------------------- | --------------------------------------------------------------------------------------------------------------- | | Exotel SIP API | https\://docs.exotel.com/dynamic-sip-trunking/detailed-sip-trunking-api-reference | | Exotel + ElevenLabs | https\://docs.exotel.com/dynamic-sip-trunking/elevenlabs-and-exotel-sip-trunking-integration-guide-for-voice-ai | | Exotel network | https\://docs.exotel.com/dynamic-sip-trunking/network-and-firewall-configuration | | ElevenLabs SIP | https\://elevenlabs.io/docs/agents-platform/phone-numbers/sip-trunking |