Question

Why is there a 40–60 minute delay when trying to reuse a deleted SIP Domain name when migrating to another Twilio subaccount?

Product

Programmable Voice, SIP Domains

Answer

The 40 to 60-minute delay before a deleted SIP Domain becomes available for reuse is expected behavior. While deletion is immediately executed at the API and account level, Twilio requires every SIP Domain to be globally unique across the entire platform. 

The delay is caused by DNS propagation, internal caching, and asynchronous background garbage collection across Twilio's distributed global edge locations. Until these global routing tables and caches fully clear, the platform treats the domain as "already in use" to prevent routing conflicts.

There is currently no way to manually expedite or force the release of a SIP Domain name once it has been deleted.

Best Practices for Migration 

Relying on the delete and recreate method carries the risk of unpredictable, extended downtime. The safest engineering standard for zero downtime is the "New Domain" cutover.

1. Provision: Create a new, slightly different SIP domain in the subaccount (e.g., yourcompany-v2.sip.twilio.com).
2. Configure: Set up your IP Access Control Lists (ACLs) and Credential Lists on this new domain.
3. Cutover: Update your on-premise equipment (PBX or SBC) to point to the new SIP domain.
4. Cleanup: Once traffic is confirmed on the new subaccount domain, delete the old domain from the main account.

Additional Information 

• Global Uniqueness: Twilio requires every SIP Domain to be unique across the entire platform. If you try to create a domain that is still clearing from the global registry, you will receive an error stating the domain already exists.
• Edge Distribution: Because SIP domains are tied to regional routing layers and edge nodes, the deletion must propagate through various global caches and DNS settings before the URI becomes available again.