StreamKit Cloud

20 min

StreamKit Developer Quickstart Guide

Bridge your Contact Centre (SIP) and Voicebot (WSS) using Exotel StreamKit Cloud Connector

1. Overview

StreamKit is Exotel’s cloud-based SIP ↔ WSS connector that allows you to connect any SIP-based contact centre (like Avaya, Genesys, Ameyo, or custom PBX) with any WSS-based AI platform (Dialogflow CX, OpenAI, AWS Lex, etc.) in real time.

This document will help you set up an end-to-end integration using:

Exotel Dynamic SIP Trunking APIs

AgentStream Applets (Stream and Voicebot / Passthru)

Custom SIP header and routing configuration

Voicebot and Agent Assist integration flows

2. Prerequisites

Requirement	Description
Exotel Account	Sign up for an Exotel account by selecting browser calling and get your Account SID, Auth Key, and Auth Token.
Virtual Number	Buy or provision a virtual number/Exophone (DID) from Exotel by reaching out to [email protected] and requesting for VoIP Exophone In case, you need the IP<>PSTN Intermix request for Veeno Exophone
SIP/IVR System	A contact centre or PBX that supports SIP INVITE routing.
Voicebot Endpoint	WSS server endpoint or AI provider URL (e.g., WebSocket URL:ws://127.0.0.1:5001/media).
IP Whitelisting	Your Contact Centre PBX/Server IPs must be whitelisted on Exotel.
Exotel Singaling and Media Ips	Your Contact Centre firewall must whitelist Exotel IPs and Ports
Test	Do test calls, routing, and in case any support is required, reach out to Exotel Phone System

3. Step-by-Step Setup

Step 1: Create an Account and Virtual Number

Signup on Exotel Link and select browser calling while signing up

Reach out to [email protected] to procure the VoIP Exophone

Once done, note:

API Settings Link

Account SID

Subdomain

Auth Key

Auth Token

Virtual Number/Exophone Link

Step 2: StreamKit Cloud SIP trunking Setup

Whitelisting ensures Exotel can securely send/receive SIP traffic from your servers.

You can add multiple IPs.

for more details refer Detailed SIP Trunking API Reference

Step 3: Set Up Your Call Flow

Use Exotel Flow Builder to define how the call moves from PSTN → SIP → WSS.

Log into Exotel Dashboard → Create a Flow

Add Voicebot Applet to connect SIP calls to your Voicebot.

Reference: AgentStream AppletsAgentStream Applet Guide

If you plan to integrate Agent Assist, use Stream Applet.

Passthru Applet.

Reference: Passthru Applet

Programmable Connect: Working with Connect Applet (Dynamic URL)Connect applet in case you want to route a call back to the contact centre

We have to add the greeting applet as the first applet with text as …

Note: if we don't add this, in that case, we will observe the voice blank issue, and the call will get disconnected in around 20 to 23 seconds

Map VoIP Exophone to the flow Using Existing Phone Number (for VoIP exophone procurement reachout to support)

Step 4: Send SIP INVITE at the Right Stage

From your Contact Centre or PBX, trigger a SIP INVITE to the Exotel SIP domain with required headers. Please do followthe mandatory headers as per the setup guide

Refer aswell Network & Firewall Configuration

Use this flow:

Customer → Contact Center (SIP PBX) → SIP INVITE → Exotel StreamKit → Voicebot (WSS)

Please do send X-Exotel-AccountSid:(Account_SID) for correct routing and CLI capture- Mandate

Step 5: Add Custom Headers

In SIP invite Contact center can pass custom headers ,

Custom headers help StreamKit voicebot applet decide which bot or campaign to route the call to.

Sample headers supported:

X-Custom-Header: SalesBot

X-UUI: XXXXXX

X-User-to-User: SalesBot

X-Campaign-ID: XXXXXX

X-Customer-ID: SalesBot

X-JWT: XXXXXX

X-Cert-Obj: XXXXXX

Supports 800 bytes per header and overall 4KB total

Note: Currently, additional custom headers above are supported on VoIP Exophone only.

Step 6: Talk to the Voicebot (WSS)

Once the SIP INVITE is accepted:

StreamKit opens a WSS connection to your voicebot.

The SIP custom headers(X-UUI and X-Custom-Headers) are supported in two ways

It is received as part of the start event custom_parameters of the Voicebot/Stream Applet

custom_parameters Key1 value is fetched from wss query params and passed at start event

Start Message received: {"event":"start","stream_sid":"b6c581dXXXXXX67a2199q","sequence_number":"1","start":{"stream_sid":"b6c581xxxxxxxxxbfe027a2199q","call_sid":"2449xxxxx1a64fbxxxx199q","account_sid":"Tenant-ID","from":"sip:0806xxxx509","to":"015xxxx0321","custom_parameters":{"Custom-Header":"Salesbot","UUI":"XXXXXXX","User-to-User":"XXXXXXX","Campaign-ID":"XXXXXXX","Customer-ID":"XXXXXXX","JWT":"XXXXXXX","Cert-Obj":"XXXXXXX","key1":"value1"},"media_format":{"encoding":"base64","sample_rate":"8000","bit_rate":"128kbps"}

Received as additional SIPCustomHeader Query parameters in https GET request of programmable applets: Passthru ,Voicebot, Stream and Connect.

GET /your-voicebot-url?CallSid={call_sid}
    &CallFrom=073XXXXXXX
    &CallTo={destination}
    &Direction=incoming
    &SIPCustomHeader[Custom-Header]=salesbot
    &SIPCustomHeader[UUI]=handoff-token-up-to-800-bytes
    &SIPCustomHeader[User-to-User]=XXXXXXXXXXXXX...
    &SIPCustomHeader[Campaign-ID]=outbound-camp-42
    &SIPCustomHeader[Customer-ID]=CUST-556677
    &SIPCustomHeader[JWT]=eyJhbGciOiJIUzI1NiJ9...
    &SIPCustomHeader[Cert-Obj]=eyJhbGciOiJIUzI1NiJ9...

RTP ↔ PCM16 media is exchanged.

Bot starts real-time ASR/TTS or speech-to-speech conversation.

Reference Doc: Voicebot Applet and bidirectional Integration Guide

Step 7: Notify or Escalate via Passthru Applet

Use Passthru Applet to notify your contact center or escalate to an agent.

Supported modes:

Notification Mode: Bot triggers webhook via Passthru Applet.

Transfer Mode: Bot requests SIP Transfer to transfer call to agent by creating another trunk at Exotel

API Steps to create a Trunk

Detailed SIP Trunking API Reference for Inbound call

Create a Flow using Connect Applet in App Bazaar

Use sip:<TrunkID> in the Dial Whom field

For custom routing, use a Dynamic URL to fetch the destination URI and pass headers

Supports up to 10 custom SIP headers, e.g.,X-*=value, X-param1=value1 (max 800 bytes each)- max 4000 bytes total

Headers prefixed with Exotel- or Veeno- are platform-reserved

Connect Applet – Dynamic URL Response Example:

{
"fetch_after_attempt": false,
"destination": { "trunk": "trunk-2134" },
"custom_params": "param1=value1&param2=value2",
"record": true,
"recording_channels": "dual"
}

Reference: Programmable Connect: Working with Connect Applet (Dynamic URL)Connect Applet – Dynamic URL

Docs: Passthru Applet (AgentStream)

4. Special Scenarios

Scenario	Description
Voicebot Mode	SIP ↔ WSS full-duplex. Bot handles ASR + TTS or speech-to-speech using Voicebot applet
Agent Assist Mode	Unidirectional WSS stream from caller to AI (for analysis, not speech output) using Stream start and stop applet
Agent Monitored Bot	Hybrid – bot monitors conversation and provides insights.
Post-Call Notify	StreamKit triggers the Passthru Applet after call completion for analytics or CRM updates.

5. Example Flow

Voicebot Scenario

PSTN Call → CC (SIP PBX) → Exotel StreamKit → WSS Voicebot

Agent Assist Scenario

PSTN Call → CC → Exotel StreamKit (Passthru) → WSS Bot (listen only)

Bot → Notify API → CRM / Dashboard

6. Compliance & Data Localization

All media and logs stay within India (Local PoPs).

DoT and TRAI voice compliance is ready.

Optional encrypted call recording with region-specific storage.

7. Quick Links

Resource	URL
Dynamic SIP Trunking	https://docs.exotel.com/dynamic-sip-trunking
Virtual SIP Trunk to Flow Guide	https://docs.exotel.com/dynamic-sip-trunking/exotel-virtual-sip-trunking-to-flow-integration-guide
AgentStream Applet	https://docs.exotel.com/exotel-agentstream/agentstream-applets
Passthru Applet	https://docs.exotel.com/exotel-agentstream/passthru-applet
Flow & API Config	https://docs.exotel.com/dynamic-sip-trunking/flow-and-api-configuration-guide-for-voice-ai-and-contact-centre-platforms