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Getting started

You need a Retell workspace, a SIP carrier or PBX, and an account in the sipsandwich application.

1. Choose how your carrier authenticates​

Select the access model your provider supports:

  • IP authentication trusts traffic based on approved source IP addresses. No SIP username or password is required.
  • Registration has sipsandwich actively sign in to the carrier using REGISTER requests.
  • SIP digest authenticates individual calls when the carrier returns a 401 or 407 challenge.

See Carrier authentication for the exact information required by each model.

2. Connect Retell​

Add a Retell API key in the application, import or select an agent, and confirm the destination configuration shown by the wizard.

3. Assign a phone number​

Map an inbound number to a Retell agent. The routing layer validates tenant policy before forwarding signaling to Retell.

4. Test signaling​

Place a test call and use the call trace tools in the application to verify the SIP route and response codes.

Automate the supported tenant API​

Workspace owners can generate a tenant API token from Settings → Security → API access. Copy the ss_api_... value when it is created and send it as a bearer token:

curl https://api.sipsandwich.ai/api/v1/sip/trunks \
  -H "Authorization: Bearer $SIPSWICH_API_TOKEN"

The public reference is intentionally limited to stable automation for Retell connection and agent sync, SIP trunks, phone numbers, outbound call creation, call history, and bounded trace sessions.