A phone call can cross several networks in seconds but establishing trust in the identity behind that call requires a carefully coordinated authentication workflow. For telecom providers the challenge is not simply signing a call — it is creating a repeatable chain of trust from origination through verification.
Modern caller authentication brings together service-provider validation, attestation, cryptographic signing, certificates, SIP signaling and verification. Understanding how these components interact helps providers build a more reliable voice trust infrastructure while avoiding unnecessary operational complexity.
STIR/SHAKEN provides one of the clearest examples of this model. Its workflow allows an originating provider to authenticate caller identity and allows a terminating provider to verify the associated identity information and signature. (TransNexus)
What Is a Telecom Authentication Workflow?
From caller identity to verified communication
A telecom authentication workflow is a sequence of technical and operational steps used to establish confidence in the identity presented with a call.
In a STIR/SHAKEN environment the simplified process looks like this:
Caller → Originating Provider → Authentication → Signed Identity → Network → Verification → Terminating Provider → Recipient
The important point is that authentication happens before the call reaches the recipient. The receiving side then evaluates the authentication information rather than simply trusting the displayed number.
Think of it like a digital passport system. The originating provider issues the identity evidence while the receiving provider checks whether that evidence is valid.
Why workflows matter
A single authentication mechanism is not enough.
Providers need processes covering:
Caller identity validation
Attestation selection
Private-key use
PASSporT creation
Certificate management
Identity header transmission
Signature verification
Certificate validation
Verification results
A structured workflow ensures these components operate together rather than becoming isolated technical functions.
Step One: Establishing the Caller and Attestation
Authentication starts with the originating provider
The first major decision occurs when an originating service provider receives the call.
The provider needs to determine whether it knows the caller and whether the caller is authorized to use the presented telephone number.
STIR/SHAKEN defines three commonly referenced attestation levels:
A — Full Attestation: The provider knows the customer and has established that the customer is authorized to use the calling number.
B — Partial Attestation: The provider knows the customer but cannot establish the customer's right to use the calling number.
C — Gateway Attestation: The provider is placing the call onto the IP network but cannot establish the necessary customer and number relationships.
Twilio's current documentation describes these same A, B and C levels and explains how they represent different degrees of confidence in caller identity. (Twilio)
Attestation is a decision based on evidence
This is important because attestation should not be treated as a simple quality label.
Consider a business customer using a number directly assigned by its provider.
The provider knows:
Who the customer is + which number was assigned + that the customer is authorized to use it
That creates the conditions for full attestation.
If one part of that relationship cannot be established the resulting attestation may be different.
Authentication therefore begins with accurate customer and number relationships.
Step Two: Creating the Cryptographic Identity
The call becomes a signed identity
Once the originating provider determines the appropriate attestation it can create the authentication information associated with the call.
The STIR/SHAKEN authentication service creates a signed PASSporT containing relevant call information and the provider's cryptographic signature. That information is carried through the SIP Identity header in a standard in-band STIR/SHAKEN flow. (TransNexus)
The process can be simplified as:
Call information → PASSporT → Hash → Private-key signature → Signed PASSporT → Identity header
The private key is critical because it allows the originating provider to create a signature that the receiving side can later verify using the corresponding public key.
Why cryptography matters
Without cryptographic signing the receiving network would have limited technical evidence that the caller identity information had not been altered.
The signature creates an integrity check.
It is similar to sealing an important document with a tamper-evident seal. The recipient does not simply trust the document because it looks legitimate. The recipient checks whether the seal can be validated.
TransNexus describes this workflow as using public-key cryptography to allow the called party's provider to verify that the calling number has not been spoofed. (TransNexus)
Step Three: Certificates Connect the Signature to a Trusted Provider
A signature needs a trusted public key
A digital signature alone does not establish who the signing party is.
The receiving provider also needs to know whether the public key used to verify that signature belongs to an authorized service provider.
This is where the STIR/SHAKEN certificate infrastructure becomes essential.
The originating provider's certificate contains the public key and relevant service-provider information. The certificate is hosted in a certificate repository so the verification service can retrieve it. (TransNexus)
The workflow therefore becomes:
Private key → Sign call → Certificate identifies public key → Repository makes certificate available → Terminating provider retrieves certificate
Certificate management is part of authentication
A certificate that has expired or cannot be retrieved can disrupt the verification process.
That is why providers need operational processes for:
Certificate issuance
Certificate publishing
Expiration monitoring
Renewal
Rotation
Revocation
Repository availability
Peeringhub's platform is specifically designed around this certificate layer. It provides a STIR/SHAKEN certificate authority service along with certificate management and developer automation. (peeringhub.io)
Step Four: Verification Happens at the Receiving Side
The terminating provider checks the evidence
When the call reaches the terminating service provider the workflow reverses.
Instead of creating the authentication evidence the receiving side evaluates it.
A simplified verification process is:
Receive Identity header → Decode PASSporT → Retrieve certificate → Validate certificate → Verify signature → Compare call information → Return verification result
TransNexus describes verification as a multi-step process in which the terminating provider retrieves the originating provider's certificate and validates the Identity header and signature. (TransNexus)
Verification is more than checking a signature
The receiving provider needs to evaluate several elements.
For example:
Is the certificate valid?
Is the issuing CA trusted?
Does the signature validate?
Does the information in the signed token correspond to the actual call?
Has the certificate expired?
These checks work together to establish whether the caller identity can be trusted.
That makes the workflow similar to airport security. Showing a passport is only one step. Authorities also check its validity, authenticity and whether the document matches the traveler.
Where Authentication Workflows Become Operationally Complex
Telecom calls rarely follow a perfectly simple path
The basic STIR/SHAKEN workflow is straightforward when a call moves through an all-IP environment.
Real telecom networks can be more complicated.
Calls may pass through:
Multiple carriers
Transit providers
SIP intermediaries
International gateways
Legacy network segments
Non-IP portions of the call path
Intermediaries are expected to preserve authentication information when passing calls through the network. Out-of-Band SHAKEN provides another approach for transporting authentication information around non-IP barriers in the call path. (TransNexus)
The workflow must survive network transitions
This creates an important operational principle:
Authentication is only useful when its trust information remains available and verifiable throughout the relevant call path.
Providers therefore need to consider authentication at an architectural level rather than treating it as an isolated feature on the originating switch.
Automating the Authentication Workflow
Manual processes do not scale efficiently
Imagine a provider manually managing every certificate request, key operation and certificate renewal.
That might be manageable for a small environment.
As infrastructure expands the same process becomes increasingly difficult to maintain.
Automation allows repetitive authentication infrastructure tasks to become predictable workflows.
Peeringhub provides an STI-ACME service compliant with RFC 8555. Its documentation describes automated certificate issuance through ACME and requires providers to have their own OCN and approved STIR/SHAKEN service-provider status before generating certificates. (doc.peeringhub.io)
Its developer API also provides workflows for authentication-token generation, private-key generation and STIR/SHAKEN certificate requests. (doc.peeringhub.io)
From manual administration to lifecycle automation
A provider can think about the process as:
Authorize → Generate key → Request certificate → Publish → Sign → Monitor → Renew → Rotate
Peeringhub's STIR/SHAKEN toolkit extends this model with reusable Python tooling for ACME workflows, CSRs, certificate inspection and validation and STI-PA SPC token handling. (GitHub)
This approach makes authentication infrastructure more programmable.
How Peeringhub compares with other approaches
Peeringhub focuses heavily on the certificate authority and developer infrastructure supporting STIR/SHAKEN. Its offering combines web-based tools, APIs, ACME workflows and certificate inspection capabilities. (peeringhub.io)
TransNexus approaches the workflow through a broader STIR/SHAKEN ecosystem covering authentication, verification, certificate management and related call-trust capabilities. Its CA supports certificate creation through web and REST API workflows. (TransNexus)
Twilio integrates SHAKEN/STIR into its broader programmable communications platform. Its workflow includes business-profile onboarding, Trust Hub vetting, phone-number association and attestation configuration through its Console or REST API. (Twilio)
The distinction is primarily about architecture and scope. Peeringhub concentrates on the trust and certificate layer while Twilio integrates authentication into a broader communications platform and TransNexus provides a wider STIR/SHAKEN ecosystem.
Conclusion: Build Authentication as a Complete Workflow
Telecom authentication is not one action performed when a call begins. It is a chain of coordinated processes that starts with establishing caller identity and continues through attestation, cryptographic signing, certificate retrieval, verification and operational monitoring.
The basic model is straightforward:
Identify → Attest → Sign → Transport → Retrieve → Verify → Trust
The complexity comes from making every stage reliable across real-world telecom environments.
For providers this means certificate management, automation and workflow visibility deserve the same attention as the signing and verification functions themselves.
Peeringhub supports this infrastructure through its STIR/SHAKEN certificate authority, ACME service, developer APIs, certificate tools and Python-based automation capabilities. (peeringhub.io)
The objective is not simply to authenticate more calls. It is to create a repeatable trust workflow that can operate reliably as the voice network grows.
Ready to simplify your STIR/SHAKEN authentication workflow? Explore Peeringhub's certificate infrastructure and build a more automated foundation for trusted voice communications.
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