1. Toll-Free Number Assignment and Administration – SHAKEN/STIR Delegate Certificates Enterprise Origination
Julio Armenta
October 3rd 2019

2. SOMOS
Somos operates the SMS/800 Toll-Free Number (TFN) Registry, the database for the management and administration of Toll-Free Numbers in the North American Numbering Plan (NANP).
The Toll-Free Number database is accessed by Toll-Free Service Providers (also known as Responsible Organizations, Resp Orgs) for reserving and managing Toll-Free Numbers.
ATIS Industry Guidelines for Toll-Free Number Administration.

3. Toll-Free Number Assignment ProcessSP
Reserves Toll-Free Number
Routing Information
Routing Data
Customer selects a Resp Org and asks for a TFN.
Resp Org reserves a TFN from the pool of available numbers in the SMS/800 TFN Registry. The TFN is marked as assigned to the Resp Org. Resp Org also provisions routing information.
Routing data is delivered to Routing DB Providers and used by SPs to route calls.
Resp Org works with Transit Networks and SPs to setup the Toll-Free service.
Enterprise is able to receive Toll-Free calls and make calls using the TFN as call back number. 2 3 3
Resp Org
( )
Routing DB
Providers 1 4 SP
Transit Network 5 5 5
Enterprise Customer

4. Responsible Organization (Resp Org)
Resp Org has been designated by the FCC as the agent for the subscriber to obtain, manage and administer Toll-Free Numbers and provide routing reference information in the SMS/800 Toll-Free Number (TFN) Registry.
Reservation, assignment, or activation of Toll-Free Numbers may only be made by a Resp Org based upon negotiations with a specific prospective Customer.
Toll-Free Numbers are assigned by Resp Orgs to their Customers from a common pool of available numbers.

5. Process To Become A Responsible Organization (Resp Org)
The process entails the following:
Online application (deposit):
Any person, company, or organization that can demonstrate the required skills and financial responsibility for managing Toll-Free Numbers can apply to become a Toll-Free Service Provider (Resp Org) in the SMS/800 Toll-Free Number Registry.
Training.
Attend a SMS/800 Toll-Free Number Registry class or self-train with materials about Toll- Free.
Successful completion of an exam on Toll-Free Industry practices.
Exam on knowledge of customer records, number administration, and service provisioning. After the exam is passed, the applicant will be certified as a Toll-Free Service Provider (Resp Org). A Resp Org ID will be assigned.

6. Resp Org Identification (Resp Org ID)
Each Resp Org is identified by a 5 character code (Resp Org ID) provided by the SMS/800 Toll-Free Number (TFN) Registry administrator.
Every Toll-Free Number reserved in the SMS/800 Toll-Free Number (TFN) Registry must have an associated Resp Org ID.
The SMS/800 Toll-Free Number (TFN) Registry Help Desk maintains the contact information associated with each operational Resp Org ID.

7. SHAKEN/STIR Delegate Certificate Management Framework For Enterprises/Business Entities
Telephone Number Provider (TN Provider): An entity that is authoritative over a set of telephone numbers, and that can delegate a subset of those telephone numbers to another entity to attest for signing.
TN Provider is authorized by the STI-PA to obtain end-user certificates from an STI-CA.
Enterprise Customers use Toll-Free numbers as callback number for contacting customers.
Responsible Organizations (Resp Orgs) are the TN Providers for Toll-Free Numbers.

8. Toll-Free Number Enterprise Originating Call
Originating SP and Resp Org are different entities.
Resp Org reserves from the pool of available numbers in the SMS/800 TFN Registry.
Resp Org assigns to Enterprise Customer.
Enterprise calls using as caller ID.
Reserves Toll-Free Number
Routing Information
Resp Org
( )
SIP INVITE
To:
From:
Originating SP
Terminating SP
Enterprise Customer

9. Recommendation
Authorize Resp Orgs to obtain end-user certificates from an STI-CA under the Delegate Certificate framework.
Authorize the use of the Resp Org ID to obtain SPC tokens.

10. Delegate Certificate For Toll-Free Number Example
Example Use Case:
TNSP-a as RespOrg (with Resp Org ID JTN01) assigns TFN to Enterprise CAF-1
Cert Management Procedure:
0) Subordinate CA (hosted by the Resp Org) obtains SPC Token from STI-PA (SPC=JTN01)
Subordinate CA obtains delegate CA cert from STI-CA
Subordinate CA issues delegate EE cert to CAF-1 (TN = )
When verifying PASSporTs signed by delegate EE cert…
STI-VS recognize that delegate CA cert TNAuthList contains a 5-character RespOrg ID
STI-VS can therefore verify that calling TFN is in-scope of delegate CA cert.
STI-CA
STI-CA Root Certificate
Issuer: STI-CA
Subject: STI-CA
STI-CA public key
Signature
CA intermediate/root cert
TFN Registry
1) Issue delegate CA certificate
RespOrg (TNSP-a)
Delegate CA Certificate
Issuer: STI-CA
Subject: TNSP-a
Basic Constraints: cA = true
TNAuthList
SPC = JTN01
TNSP-a public key
Signature
Certificate path
Subordinate CA
Delegate CA cert
2) Issue delegate end-entity certificate
Constrains Scope
Delegate end-entity Certificate
Issuer: TNSP-a
Subject: CAF-1
TNAuthList
TN =
CAF-1 public key
Signature
VoIP Entity (CAF-1)
Delegate end-entity cert

11. Thank you.