Skip to main content

Programmable Voice APIs with AgentStream

Full runtime control via Legs API — per-call stream URLs, dynamic routing, and greeting + stream in parallel.

Works for outbound (POST /legs) and inbound (Exophone attached to a gRPC endpoint). See What to use when.

Authentication​

HTTP Basic Auth — API Key as username, API Token as password.
Content-Type: application/json

Base URL: https://cpaas-api.in.exotel.com/v2/accounts/{account_sid}
(Singapore: cpaas-api.exotel.com)

Create leg (dial)​

Request parameters​

ParameterRequiredTypeDescription
contact_uriYesStringNumber to dial (E.164)
exophoneYesStringYour ExoPhone
leg_event_endpointYesStringgRPC endpoint for leg events
timeoutNoIntegerRing timeout in seconds

Example request​

curl -u '<api_key>:<api_token>' -X POST \
  'https://cpaas-api.in.exotel.com/v2/accounts/<account_sid>/legs' \
  -H 'Content-Type: application/json' \
  -d '{
    "contact_uri": "+919876543210",
    "exophone": "08047491899",
    "leg_event_endpoint": "grpc://your-event-server.example.com",
    "timeout": 30
  }'

Try It​

Exotel emits: leg_connecting → leg_ringing → leg_answered

Start stream​

Call on leg_answered.

Request parameters​

ParameterRequiredTypeDescription
directionYesStringbidirectional for Voice AI
urlYesStringBot WebSocket URL (wss://)
content_typeNoStringe.g. audio/x-mulaw;rate=8000

Example request​

curl -u '<api_key>:<api_token>' -X POST \
  'https://cpaas-api.in.exotel.com/v2/accounts/<account_sid>/legs/<leg_sid>/actions/start_stream' \
  -H 'Content-Type: application/json' \
  -d '{
    "direction": "bidirectional",
    "url": "wss://bot.example.com/stream",
    "content_type": "audio/x-mulaw;rate=8000"
  }'

Try It​

Optional — greeting while stream initialises​

Fire with start_stream on leg_answered to avoid dead air.

Start say​

curl -u '<api_key>:<api_token>' -X POST \
  'https://cpaas-api.in.exotel.com/v2/accounts/<account_sid>/legs/<leg_sid>/actions/start_say' \
  -H 'Content-Type: application/json' \
  -d '{ "text": "Please hold.", "loop": 0 }'

Try It​

Stop say​

Call on stream_started:

curl -u '<api_key>:<api_token>' -X POST \
  'https://cpaas-api.in.exotel.com/v2/accounts/<account_sid>/legs/<leg_sid>/actions/stop_say'

Try It​

ScenarioUse greeting?
Inbound IVR / tech supportUsually no
Outbound sales / collectionsYes

Inbound ExoML​

  1. Implement a gRPC leg-event endpoint
  2. Attach the Exophone to that endpoint (not to an App Bazaar flow)
  3. On inbound leg_answered, issue start_stream (and optional say/play)

No Voicebot applet required — your service is the flow.