How to Configure an Exotel SIP Trunk with Voice AI in 2026

Connecting your existing telephony infrastructure to conversational AI is the fastest way to automate customer interactions without losing your established business numbers. Bolti, a voice AI platform for building production-ready conversational phone agents, makes this integration seamless.

By routing your exotel sip trunk to Bolti, you get the best of both worlds: Exotel's reliable Indian telecom routing and Bolti's sub-second conversational latency. Whether you are running outbound lead qualification, automated customer support, or payment reminders, bringing your own carrier (BYOC) keeps your telecom costs low while maintaining full control over your caller ID.

With Bolti's transparent pricing of ₹6/min pay-as-you-go and a free trial that includes 50 minutes, you can connect your SIP trunk and place your first AI-powered call in less than 15 minutes.

What is an Exotel SIP Trunk and Why Use It with Voice AI?

An Exotel SIP trunk is a virtual phone line that uses the Session Initiation Protocol (SIP) to connect your business's private branch exchange (PBX) or cloud telephony system to the public switched telephone network (PSTN). In simpler terms, it is the digital pipe that carries your voice calls over the internet.

Integrating this trunk with Bolti's voice AI engines provides several key operational advantages:

• Keep Your Caller ID: You do not need to buy new numbers. Your customers will see the same trusted business numbers they already recognize.
• Lower Telecom Costs: Instead of paying markup fees on minutes, you pay Exotel directly for your SIP trunk usage at your negotiated enterprise rates.
• Local Indian Routing: Exotel is built for the Indian telecom ecosystem, ensuring high call-completion rates, clean CLI (Caller Line Identification), and compliance with local regulations.
• Multilingual Capabilities: Combine Exotel's stable routing with Bolti's native support for Indian languages including Hindi, Marathi, Tamil, Telugu, Bengali, and Gujarati.

Step-by-Step: How to Connect Your Exotel SIP Trunk to Bolti

To wire an Exotel number to a Bolti conversational agent, you will configure the connection in your Bolti dashboard. Here is how to complete the setup.

Step 1: Add the Exotel Integration in Bolti

First, you need to establish the authentication link between Bolti and your Exotel account. This allows Bolti to recognize and fetch your active numbers.

1. Log in to your Bolti dashboard.
2. Navigate to Integrations in the left-hand navigation menu.
3. Select Exotel from the list of supported telephony providers.
4. Enter your Exotel Account SID, API Key, and API Token. You can retrieve these credentials from your Exotel developer console.
5. Click Save. Your Exotel account is now connected as a provider.

Step 2: Configure Your Inbound and Outbound Trunks

Once the provider integration is active, you can configure your numbers under the Phone Numbers tab in the left sidebar. This is where you register your inbound-capable SIP trunks and DIDs.

• Go to Phone Numbers.
• Verify that your Exotel DIDs are visible. If you are bringing a custom SIP trunk configuration, register it as an inbound-capable trunk.
• Ensure all phone numbers are formatted in strict E.164 format (e.g., starting with +91 followed by the 10-digit mobile or landline number, such as +919876543210). Bolti rejects non-E.164 input with an inline error.

Step 3: Assign the Number to Your Voice Agent

Now that Bolti recognizes your Exotel number, you must assign it to a specific AI agent so that incoming calls are routed correctly.

1. Navigate to Agents and select the agent you want to configure.
2. Click on the Phone tab within the agent's settings.
3. Scroll to the Assign New Number panel at the bottom.
4. In the Select Trunk dropdown, choose your configured Exotel trunk.
5. In the Select Phone Number dropdown, choose the specific E.164-formatted DID number you want to assign.
6. Click Assign Number.

The assignment takes effect immediately. The next incoming call to that Exotel number will automatically route to your Bolti voice agent.

Optimizing Your Voice Stack for Indian Languages

Telephony is only one part of the equation. To make your Exotel-routed calls sound natural and human-like, you must configure the rest of your voice AI stack. Every call on Bolti uses four distinct providers: Speech-to-Text (STT), the Large Language Model (LLM), Text-to-Speech (TTS), and Telephony (Exotel).

When optimizing for Indian business contexts, consider these specific provider selections in your agent's Speech and LLM tabs:

• STT (Speech-to-Text): For calls in Hindi, Tamil, Telugu, or mixed "Hinglish", choose Fennec or Sarvam-backed STT. These models are specifically optimized for Indian accents and multilingual code-switching, outperforming global alternatives.
• LLM (The Brain): If you need ultra-low latency for simple transactional calls, select Groq Llama models. For complex, branching customer support queries where the agent needs to fetch account details via APIs, use Gemini 2 Flash or GPT-4o-mini.
• TTS (Text-to-Speech): To ensure your agent sounds natural, select Indian-accented English or native-language voices from SarvamAI or Cartesia to maintain high expressiveness over the phone.

To see how different industries configure these stacks to automate millions of minutes, explore our Bolti use cases.

Managing Inbound vs. Outbound Calls on Your Exotel Trunk

Routing behaves differently depending on whether your AI agent is receiving or making calls. Understanding this distinction prevents configuration mistakes:

Inbound Calling

Inbound calling requires explicit mapping. You must assign your Exotel DID to a specific agent in the Phone tab as described in Step 3. Incoming calls will only route to the agent that currently holds the "Assigned" badge for that number. You can reassign or unassign numbers at any time from the Phone Numbers page.

Outbound Calling

For outbound campaigns, you do not assign numbers inside the agent's Phone tab. Instead, Bolti's outbound dialer can use any outbound-capable number available on your workspace. You choose which Exotel caller ID to use at the moment you initiate the dial sequence—either via the Make Outbound Call dialog in the dashboard or programmatically using Bolti's REST API.

Try Bolti with Your Exotel SIP Trunk

Setting up an automated voice agent does not require migrating your entire telecom infrastructure. With Bolti, you can connect your existing Exotel numbers and start running production-grade voice workflows with sub-second latency and advanced interruption handling.

Spin up your first Exotel-powered voice agent in under 10 minutes—start your free trial with 50 minutes or view our Bolti pricing details to see how our ₹6/min flat rate fits your budget.

Frequently Asked Questions

How do I format my Exotel numbers in Bolti?

All phone numbers in Bolti must be entered in strict E.164 format. This means they must start with a '+' followed by the country code and the phone number without any spaces, dashes, or leading zeros (e.g., +919876543210 for India). Non-E.164 inputs will return an error.

Can I use the same Exotel number for both inbound and outbound calls?

Yes. You can assign an Exotel number to an agent for inbound routing in the Phone tab, and also select that same number as your caller ID when triggering outbound calls via the dashboard or API.

Does Bolti charge extra if I bring my own Exotel SIP trunk?

No. Bolti's platform rate remains a flat ₹6/min pay-as-you-go. You will pay your standard telecom and SIP trunking rates directly to Exotel, allowing you to keep your negotiated carrier pricing.

How fast does the AI agent respond over an Exotel SIP trunk?

Bolti is engineered for sub-second conversational latency. When paired with high-quality routing like an Exotel SIP trunk and low-latency STT/TTS providers, the round-trip response time is typically under 800ms, making the conversation feel natural and human-like.