International Restrictions & Twilio Geo Permissions for Phone Numbers

When using Twilio phone numbers within Synthflow, especially for international calling, it's important to configure your Twilio account correctly and understand any geographic restrictions that may impact calling or SMS.

Common International Restrictions

1. Blocked Countries by Default

   • Twilio blocks most international destinations by default to prevent fraud or accidental charges.

   • You must manually enable calling to specific countries from your Twilio console.

2. High-Cost or High-Risk Regions

   • Some countries (e.g., Cuba, North Korea, parts of Africa) are either restricted or require elevated verification.

   • SMS may not be deliverable in certain countries even if voice calls are supported.

3. Carrier Filtering

   • Even when calls are enabled, local carriers in some countries may block or filter calls/SMS if the caller ID appears invalid or unverified.

Enabling Geo Permissions in Twilio

To allow international calls from your Synthflow AI agent using Twilio numbers:

Step-by-Step: Allow Outbound International Calls

1. Login to Twilio Console

   • Visit: https://console.twilio.com

2. Navigate to Voice Settings

   • Go to Voice → Settings → Geo Permissions (Voice)

3. Enable Countries

   • You’ll see a list of countries categorized by continent.

   • Check the boxes for the countries you want to allow outgoing calls to.

4. Save Changes

   • Always click “Save” at the bottom to apply your geo permissions.

For SMS:

• Go to Messaging → Settings → Geo Permissions (SMS) to configure separately if using SMS flows.

Tips for Safe International Usage

• Limit to only necessary countries to avoid unexpected costs.

• Use verified numbers for improved delivery and call acceptance rates.

• Consider using Twilio usage alerts or spend caps to monitor costs.

Common Issues

For more help setting up Twilio numbers or testing international routes, contact Synthflow support or refer to Twilio’s Voice Geo Permissions Guide.