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Connect phone numbers to your voice agents for outbound and inbound calls. Telephony is configured in the Telephony section of the Dashboard, where you manage two kinds of connections (SIP trunks):
  • Outbound connections — let an agent place calls and run human transfers
  • Inbound connections — route incoming calls on your numbers to an agent
For both, you can use the guided Twilio setup or the Manual setup for any generic SIP provider (BYOC).

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Outbound calling

Outbound calls require an outbound connection.
1

Create an outbound connection

Open Create outbound connection in the Dashboard. Pick the Twilio guided setup or the manual setup, then configure the termination host, transport, SIP credentials, and the caller ID number(s).
2

Attach it to your agent

In the agent editor’s Telephony tab, select the connection under Outbound calls. See Assigning connections to an agent.
Without an outbound connection, call dispatch via the API (POST /v1/agents/{agent_id}/calls) fails.

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Caller ID pool

An outbound connection can carry more than one phone number. The numbers form a rotating caller ID pool: if you add multiple numbers, SLNG selects one number at random for each call. You can change the pool at any time by editing the connection from the Telephony page. Unlike inbound connections, a single outbound connection can be attached to multiple agents.

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Inbound calling

To route incoming calls to a specific agent, create an inbound connection:
1

Create an inbound connection

Open Create inbound connection and add the phone number(s) that should reach the agent. In manual mode you can also restrict which source addresses are allowed; the Twilio guided setup walks you through pointing your Twilio number at SLNG.
2

Assign an agent

You can assign an agent directly in the creation flow, or later from the agent editor’s Telephony tab. An inbound connection can only be assigned to one agent at a time.

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Assigning connections to an agent

The Telephony tab of the agent editor has a picker for the inbound connection (incoming calls) and one for the outbound connection (outbound calls and human transfers). Connections that can’t be assigned appear disabled and marked (Unavailable), with the reason shown:

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Save-time validation

Two agent-editor rules depend on telephony, checked when you save:
  • Directional greetings (separate inbound/outbound greetings on the Design tab) require at least one connection — inbound or outbound — to be assigned.
  • Human transfer tools require an outbound connection, since the transfer places an outbound call.
The same rules apply when importing an agent configuration — the import flow asks you to pick an outbound connection if the config needs one. See Import, export, and duplicate.