docs: clarify Twilio inbound SIP gateways#1099
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@stephenvapiai could you take a look? A customer's Twilio trunk worked outbound but inbound was blocked because our guide did not explain that Twilio's source signaling CIDRs must be added as separate inbound-only gateways. This adds the concrete EU example, explains why the termination FQDN is outbound-only, and links to Twilio's live IP list. |
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Looks good to me! Thanks for making the updates!
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🌿 Preview your docs: https://vapi-preview-019f3f11-c545-741e-a48e-054d8148236f.docs.buildwithfern.com |
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Description
Problem: A Twilio trunk can work for outbound calls while inbound calls are silently blocked if the Vapi credential contains only the Twilio termination hostname.
This explains the split in simple terms: the termination hostname is for outbound routing, while inbound trust uses Twilio's published numeric signaling networks.
fern/advanced/sip/sip-twilio.mdxwith a concrete Dublin/Frankfurt example, directional gateway flags,/30netmask syntax, and a link to Twilio's live IP list.fern/advanced/sip/troubleshoot-sip-trunk-credential-errors.mdxso customers use provider-published source networks instead of assuming an outbound hostname resolves to the inbound source addresses.Related: PRISM-1200 and VapiAI/vapi#14042. The product fix and this docs fix are separate PRs, so this PR does not auto-close the shared ticket.
Testing Steps
fern check-- passes with 0 errors. The 5 warnings are existing spec, authentication, and theme warnings.54.171.127.192/30and Frankfurt35.156.191.128/30networks against Twilio's current Elastic SIP Trunking IP address page.gateways,netmask,inboundEnabled, andoutboundEnabledagainst the Vapi credential schema and source fix.