Joint Trades Letter to ATIS/SIP Forum NNI Task Force re: Standard for SIP Code 603+

ATIS/SIP Forum NNI Task Force
733 Turnpike Street, Suite 192
North Andover, MA 01845

Dear Members of the ATIS/SIP Forum NNI Task Force,

The American Bankers Association, ACA International, American Financial Services Association, Credit Union National Association, Mortgage Bankers Association, National Association of Federally-Insured Credit Unions, National Council of Higher Education Resources, and Student Loan Servicing Alliance (collectively, the Associations) appreciate the opportunity to provide feedback on the standard that the ATIS/SIP Forum NNI Task Force (Task Force) is developing for telephone companies that block calls and their analytics providers (collectively, Voice Service Providers or Providers) to use Session Initiation Protocol (SIP) Code 603 to notify the caller that its call has been blocked.

As you know, SIP Code 603 was initially designed to signal that the recipient “decline[d]” the call. In the Federal Communications Commission’s (Commission) Order on Reconsideration issued on December 30, 2021, the Commission permitted Voice Service Providers to use SIP Code 603, in addition to SIP Codes 607 or 608, to satisfy the Commission’s requirement promulgated in 2020 that a Provider immediately notify callers when it has blocked the caller’s call. We have expressed concern to the Commission that, under the Order, a caller receiving a SIP Code 603 response would not be able to understand whether the response code signaled that the call’s recipient declined the call or that the Provider blocked the call in the network.

We understand that the Task Force is developing an enhanced version of SIP Code 603 (SIP Code 603+) that would allow the caller to distinguish between a 603+ Code that indicates the called party declined the call from the receipt of a 603+ Code that signals that the Voice Service Provider blocked the call. In response to your suggestion that the Associations identify issues important to the calling community when receiving blocking notification, we provide the following:

1. SIP Code 603+ must utilize a uniform, standard word or phrase in the header of the code that clearly indicates that the call has been blocked in the network based on the use of analytics. The current iteration of the Task Force’s base document for the standard for SIP Code 603+ suggests using the reason phrase “Network Blocked” for this purpose. It should be made clear, including through a revision of documentation for SIP Code 603 maintained by the Internet Engineering Task Force (IETF) (the body that sets generic standards for internet protocols) that Providers blocking calls in the network based on analytics shall use only a standardized uniform reason phrase.
2. The standard for a 603+ Code must enable the code to be read using automated, machine-readable technology.
3. It should be clear that a 603+ Code without a reason header signifies the called party has declined the call, per existing IETF documentation. A 603+ Code with the uniform standard reason phrase shall signify network blocking by analytics. A 603+ Code should not be used for any other purpose.
4. The reason header must include, in standardized formats, the name and contact information for the blocking entity.
5. The standard for SIP Code 603+ should address, to the extent practicable, the transmission of the 603+ Code across international boundaries. Specifically, SIP Code 603+ must be able to provide effective notification in the following instances: (1) where the caller is located in the United States, and the call recipient is located outside the U.S.; (2) where a U.S. company caller placed the call from a location outside of the U.S. to a recipient outside the U.S.; (3) where a U.S. company caller placed the call from a location outside of the U.S. to a recipient inside the U.S.; (4) where a U.S. company caller placed the call from a location within the U.S. to a recipient within the U.S., but the call was blocked by an intermediary provider that is located outside of the U.S.; and (5) where the subsidiary of an international Voice Service Provider that is providing services in the U.S. blocks a call.
6. The standard for SIP Code 603+ should address which entity should receive notification where a third party initiates the call on behalf of a customer, for example, where a call center it utilized.
7. To the extent practicable, the standard for SIP Code 603+ should consider cost of deployment and implementation by small carriers and both large and small enterprise callers.
8. The standard for SIP Code 603+ should ensure that callers’ calling applications are able to interrogate the header on the 603+ Code. Currently, the response codes that callers receive (SIP “call traces”) are cumbersome for callers to examine, and callers’ calling applications will need to be re-programmed so that they interrogate the header of the response codes.

Thank you for consideration of these views. We look forward to continued discussion of the standards for SIP Code 603+.

Sincerely,

American Bankers Association
ACA International
American Financial Services Association
Credit Union National Association
Mortgage Bankers Association
National Association of Federally-Insured Credit Unions
National Council of Higher Education Resources
Student Loan Servicing Alliance