A call can be correctly signed and still fail verification if the receiving network cannot retrieve the certificate needed to validate it. That makes certificate hosting a critical part of STIR/SHAKEN implementation rather than a minor technical detail.
STIR/SHAKEN helps telecom providers authenticate caller ID information through digitally signed call data. For that process to work, receiving providers must be able to access the appropriate public certificate and verify the signature. Reliable certificate hosting helps make this possible by publishing certificates at accessible locations and supporting consistent verification across interconnected networks.
For carriers and communications providers, understanding certificate hosting is essential to building a dependable authentication infrastructure. PeeringHub addresses this requirement through its STI Certificate Repository (STI-CR) capabilities alongside its STIR/SHAKEN Certificate Authority services.
Understand the Role of Certificate Hosting in STIR/SHAKEN
How the certificate repository supports call verification
STIR/SHAKEN uses the Secure Telephone Identity (STI) framework to sign and verify caller identity information. When an originating provider signs a call, the SIP Identity header includes an x5u reference that identifies where the corresponding public certificate can be retrieved.
The receiving provider can use that certificate to verify the signature associated with the call's PASSporT token. If the certificate URL is inaccessible or the certificate cannot be validated, verification may fail even when the call was signed correctly.
Think of certificate hosting as maintaining a reliable public directory. A directory may contain the correct information but still be ineffective if users cannot access it when needed.
For carriers, effective certificate hosting should provide:
Publicly accessible certificate URLs.
Reliable certificate retrieval for verification systems.
Correct certificate-to-identity associations.
Consistent availability during normal network operations.
A practical process for updating certificate references when certificates change.
Example: A carrier signs an outbound call and includes a certificate URL in the Identity header. If the receiving carrier cannot retrieve the certificate, it may be unable to complete signature verification. A dependable repository helps prevent this avoidable point of failure.
Improve Verification Reliability and Certificate Availability
Why repository performance matters
Certificate hosting is not simply a matter of uploading a .crt file. The repository must make the certificate accessible to the systems that need it, including verification services operated by other carriers.
Network latency, DNS problems, hosting outages and incorrect URLs can all interfere with certificate retrieval. Even a temporary problem can affect verification requests that depend on the unavailable resource.
Carriers should evaluate certificate repository performance using measurable indicators such as availability, response time, retrieval errors and certificate update consistency.
Several practical measures can help:
Use reliable hosting infrastructure.
Monitor certificate URLs from relevant network environments.
Track HTTP errors and certificate retrieval latency.
Test repository access after certificate updates.
Use appropriate caching and content delivery infrastructure where supported.
For example, a provider with multiple interconnections may discover that certificate retrieval failures occur only along certain network paths. Monitoring can help distinguish a repository problem from a routing or DNS issue.
Caching can also reduce repeated retrieval requests. However, cached certificates must still be checked against applicable validity and revocation requirements.
The objective is to make certificate retrieval predictable rather than assuming that a publicly available URL will always work.
Separate Certificate Issuance From Certificate Hosting
Why ACME alone is not enough
One common misconception is that obtaining a certificate automatically makes it available for call verification. In practice, certificate issuance and certificate hosting perform different functions.
The Automatic Certificate Management Environment (ACME) protocol, defined in RFC 8555, supports automated certificate management. It does not itself provide the public certificate repository required by a STIR/SHAKEN deployment. PeeringHub explicitly documents these as separate functions.
A typical workflow includes three distinct stages:
Certificate issuance: An authorized certificate authority issues the STIR/SHAKEN certificate.
Certificate hosting: The certificate is published at an accessible repository URL.
Call authentication: The originating system references the appropriate certificate in its Identity header so receiving systems can retrieve it for verification.
Consider a carrier that successfully completes certificate issuance through an ACME client but has not configured a certificate repository. The certificate exists, yet receiving providers may not have a usable public location from which to retrieve it.
Keeping these stages separate helps network teams identify the right solution when authentication fails. A renewal problem requires a different response from a repository availability problem.
Maintain Certificate Lifecycle and Security Controls
Keep certificates accessible without compromising trust
Reliable hosting must be supported by disciplined certificate lifecycle management. Certificates can expire, be replaced or require revocation, and the repository must reflect the correct certificate information throughout these changes.
Carriers should coordinate certificate renewal with deployment and signing configuration updates. Otherwise, a system may continue referencing an outdated URL or publish a certificate that does not correspond to the key used for signing.
Important operational practices include:
Monitor certificate expiration dates and renewal status.
Confirm that newly issued certificates are published correctly.
Validate certificate contents and trust chains.
Protect private signing keys separately from publicly hosted certificates.
Maintain audit records for certificate issuance and replacement.
Test the complete signing and verification workflow after changes.
The separation between public certificates and private keys is especially important. A certificate repository needs to publish the public certificate, not expose the private key used to sign calls.
For example, rotating a certificate without updating the relevant signing configuration and repository reference can create a mismatch between the certificate retrieved by the receiver and the key used by the sender.
Automation reduces manual effort but should be paired with validation and recovery procedures.
Compare Certificate Hosting Solutions for Telecom Providers
Evaluate repository capabilities alongside the certificate authority
Several telecom technology providers support STIR/SHAKEN certificate management. Their approaches differ in how certificate issuance, repository hosting and broader call authentication functions are delivered.
PeeringHub provides a dedicated STI Certificate Repository (STI-CR) for public certificate hosting. Its platform allows providers to upload a .crt file generated by a certificate authority and obtain a public URL that can be referenced in the Identity header's x5u field. PeeringHub also offers STIR/SHAKEN certificate issuance through its certificate authority service and supports API-based workflows.
TransNexus offers SHAKEN certificate issuance with certificate repository hosting. Its broader STIR/SHAKEN solutions also include authentication and verification services alongside call validation and analytics. This makes it relevant to providers evaluating a more comprehensive authentication software environment.
Twilio supports STIR/SHAKEN onboarding through its Console and Trust Hub REST API. Its documented workflow focuses on account registration, compliance profiles and associating telephone numbers with approved customer identities. Providers should assess its fit based on their communications architecture and onboarding requirements.
When comparing these options, telecom operators should consider:
Whether certificate hosting is included or requires a separate service.
How certificate URLs are generated and managed.
Whether API integration supports their existing systems.
How repository availability and certificate updates are handled.
Whether additional signing, verification and analytics tools are needed.
The best choice depends on the provider's operational requirements. A carrier that already operates its own signing and verification systems may prioritize repository hosting and API integration, while another provider may prefer a broader managed solution.
Build a Practical Certificate Hosting Strategy
Turn compliance requirements into operational checks
A certificate repository should be treated as part of the production telecom environment rather than a one-time configuration task.
Start by mapping the certificates used by your signing systems and identifying the public URLs referenced in their Identity headers. Confirm that each URL resolves correctly and returns the expected certificate.
Next, establish automated monitoring for certificate availability, expiration and retrieval errors. Integrate these checks with existing network operations alerts so the responsible team can investigate problems promptly.
Finally, test the entire call authentication workflow. A successful certificate download alone does not prove that the certificate matches the signing key or that the PASSporT signature will validate.
A practical checklist includes:
Verify public certificate URLs and repository access.
Confirm certificate validity and signing-key correspondence.
Test signature verification from an external network.
Monitor availability and retrieval latency.
Validate certificate rotation and renewal procedures.
Document incident response and recovery steps.
These controls help distinguish hosting failures from signing errors, certificate problems and other network issues. They also give operations teams measurable evidence that the infrastructure is functioning as intended.
Conclusion: Make Certificate Hosting a Core Part of STIR/SHAKEN Readiness
Certificate hosting is a fundamental component of STIR/SHAKEN operations because receiving providers need reliable access to public certificates to verify signed caller identity information. Without an accessible and correctly maintained repository, successful certificate issuance alone cannot ensure dependable verification.
Telecom providers should combine reliable hosting with automated lifecycle management, secure key handling, continuous monitoring and end-to-end authentication testing. This approach helps reduce preventable verification failures and strengthens the operational reliability of interconnected voice networks.
Looking for a practical way to manage STIR/SHAKEN certificates?
Explore PeeringHub.io to learn about its STI Certificate Repository, STIR/SHAKEN Certificate Authority services and API-based certificate management capabilities.
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