Call Directions
Call Directions
Outbound (SIP → PSTN)
Calls initiated from your SIP system to external phone numbers.
Call path:
Used for:
- Agent outbound calling
- Dialers and campaigns
- Click-to-call from CRM
- Alerts and notifications
Key requirements:
- IP whitelisting (ACL) on the trunk
- Phone number mapped to trunk (Caller ID)
Inbound (PSTN → SIP)
Calls initiated from the telephone network to your SIP system.
Call path:
Used for:
- Customer support lines
- Sales inbound numbers
- IVR and call routing to PBX
Key requirements:
- DID mapped to an Exotel Flow
- Flow uses Connect Applet with sip:<trunk_sid>
- Destination URI configured on the trunk (IP or FQDN)
Bidirectional (SIP ↔ PSTN)
The same SIP Trunk is used for both outbound and inbound calls.
Call paths:
Used for:
- Contact centers
- PBX integrations
- Unified inbound + outbound calling
- Agent calling with inbound callbacks
Key requirements:
- Phone number mapped to trunk
- IP whitelisting enabled (for outbound)
- Destination URI configured (for inbound)
- Exotel Flow with Connect Applet (sip:<trunk_sid>)
This is the most common SIP Trunking setup.
Routing Modes
Routing mode defines how Exotel handles calls once they reach the DID/Exophone/Virtual Number.
The mode is set while mapping a phone number to a trunk.
mode: pstn (Default)
Standard telephony routing.
Used for:
- Outbound calls to PSTN
- Inbound calls routed to SIP systems
- Bidirectional SIP Trunking
- Flows using Connect Applet (sip:<trunk_sid>)
Behavior:
- Calls behave like standard SIP/PSTN calls
- Media flows directly between Exotel and your SIP system
- No Voice AI or Flow applet execution
mode: flow
Flow-controlled routing.
Used for:
- Voicebot / AI integrations
- App Bazaar applets
- StreamKit use cases
Behavior:
- Calls are routed into Flow execution
- Audio may be streamed to Voice AI platforms
- Required for Voicebot and other non-Connect applets
Mode Selection Summary
Use Case | Flow Applet Used | Mode |
|---|---|---|
Outbound only | None | pstn |
Inbound only | Connect (sip:<trunk_sid>) | pstn |
Bidirectional SIP Trunk | Connect (sip:<trunk_sid>) | pstn |
Voicebot / AI | Voicebot / Applets | flow |
Important Notes
- Destination URI is mandatory for all SIP Trunking setups
- Flow is mandatory for inbound calls
- mode controls call handling, not trunk termination
Bidirectional uses the same trunk for inbound and outbound