List retry attempts for a call

Returns the parent call plus every retry attempt that branched from it, ordered by attempt index. Use this when a customer asks "did the platform retry this call?" — typically driven by an outbound agent's auto-retry configuration (maxRetries, retryDelay).

• If the callId you pass is the original (parent), the response contains that parent plus all child retries.
• If the callId you pass is itself a retry, the response still includes the parent and every sibling retry — the API resolves to the family root automatically.

Returns 404 if no call exists with that ID in your organization.