Problem calling a Peruvian

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To enable calling to countries not supported by Retell-purchased numbers, you can use Elastic SIP Trunking to connect your own phone number from a telephony provider that supports your target country(1).

Setting Up SIP Trunking for International Calls:

Step 1: Create Elastic SIP Trunking with Your Provider

Set up a SIP trunk with a provider like Twilio, Telnyx, or Vonage(1)(2)(3). Configure both termination (outbound) and origination (inbound) settings(1)(2)(3):

  • For termination, note your provider’s termination SIP URI(2)(3)
  • For origination, set Retell’s SIP server address as: sip:sip.retellai.com(1)
  • Configure authentication via IP whitelisting or credentials(2)

Step 2: Enable International Dialing in Your Provider

For providers like Twilio, search “geo” to find the “Voice Geographic Permissions” setting and select the countries you want to dial(2)(4). Choose “Elastic SIP Trunking” in the selector and enable your target countries(2).

Step 3: Import Your Number to Retell

Import your number to Retell via the dashboard or API, providing(1)(2)(3):

  • The termination SIP URI from Step 1
  • Username and password if using credential-based authentication
  • The outbound_allowed_countries parameter with country codes (e.g., “PE” for Peru)(4)

When creating or updating a phone number, specify outbound_allowed_countries as a list of ISO 3166-1 alpha-2 country codes(4). If not set or empty, calls to all countries are allowed by default, but your telephony provider must also support those destinations(4).

Supported Transport Methods:

For different transport methods, append to the SIP server URL (e.g., sip:sip.retellai.com;transport=tcp)(1).