FCC Expands Call Blocking Requirements for Voice Service Providers
On February 27, 2025, the Federal Communications Commission (FCC or Commission) adopted an Eighth Report and Order (Order) expanding the Commission’s rules targeting illegal robocallers. The Order extends the requirement to block voice traffic based on a reasonable do-not-originate (DNO) list to all providers in the call path, and it modifies the Commission’s rules requiring terminating voice service providers to immediately notify callers of voice traffic blocked based on reasonable analytics using Session Initiation Protocol (SIP) code 603+.
The Order continues the Commission’s ever-increasing requirements for voice service providers to take steps to mitigate illegal robocalling, building most recently on the January 2025 Report and Order that imposed new requirements and fees for Robocall Mitigation Database (RMD) filers. These latest call blocking rules, which will apply differently to various voice service providers throughout the call chain, are discussed in greater detail below.
All Providers in Call Path Required to Block Traffic Based on DNO List.
The Order expands DNO blocking requirements to apply to all providers in the call path. Prior to this new Order, blocking voice traffic based on a “reasonable” DNO list was only mandated by the Commission for gateway providers and messaging providers; however, now, there is a similar requirement for all voice service providers.
The Order’s expanded DNO blocking mandate operates similarly to the existing DNO rules for gateway providers and messaging providers. In particular, with the newest rules, the Commission declines to mandate the use of a specific list or establish a minimum list, allowing voice service providers to use any DNO list “so long as the list is reasonable.” In determining reasonability, the Commission reserves the right to “deem unreasonable a list so limited in scope that it leaves out obvious numbers that could be included with little effort.”
The expanded DNO blocking mandate becomes effective 90 days after publication of notice of Office of Management and Budget (OMB) approval in the Federal Register.
Providers Required to Utilize Uniform SIP Code for Immediate Notification of Analytics-Based Blocking.
The Order also updates the Commission’s current requirements related to notifying callers when certain calls are blocked.
First, the Order modifies the existing rule for terminating providers to provide immediate notification to callers when calls are blocked by the provider based on reasonable analytics, to exclusively mandate the use of SIP code 603+. Prior to this new Order, the FCC required such notifications but temporarily permitted providers to use one of several SIP codes for immediate notification of blocking based on an analytics program (i.e., SIP codes 603, 607, or 608). In modifying this rule, the Commission directs terminating providers to sunset the use of SIP codes 603, 607, and 608, and to perform software upgrades as necessary to ensure that the 603+ code is properly mapped. Specifically, the Order requires providers to implement the 603+ code no later than 12 months from publication of the Order in the Federal Register; the same 12-month deadline is imposed for providers to cease using SIP codes 603, 607, and 608 for notification of analytics-based blocking.
The Order addresses several operational issues related to this immediate notification. In relevant part:
- Immediate notification using the SIP 603+ code is required only for analytics-based blocking, not blocking based on a DNO list, blocking pursuant to Commission notification not based on analytics, or at the request of a customer without the use of analytics.
- Providers are permitted to continue to use SIP code 603 where appropriate, but not for analytics-based blocking, except for when an intermediate or terminating provider receives ISDN User Part (ISUP) code 21 and cannot determine whether SIP code 603 or 603+ is appropriate. Similarly, SIP code 607 may continue to be used in instances where calls are blocked at a subscriber’s discretion, but not when calls are blocked by the provider based on reasonable analytics.
- For calls that transit over Time Division Multiplexing (TDM) and IP networks, the Order confirms that the correct ISUP code for immediate notification based on the use of reasonable analytics remains 21.
Beyond requirements for terminating providers, the Commission further clarifies that all providers in the call path must transmit the appropriate code to the origination point of the call, including ensuring that the 603+ code appropriately maps to ISUP code 21. IP Providers are similarly required to ensure that they transmit the full header contained in the 603+ code, including all mandatory text fields established in the standard.
FCC Declines to Regulate Rich Call Data and Other Caller Name Tools.
Finally, the Commission’s Order declines to further regulate caller ID offerings but encourages industry to continue to develop tools like Rich Call Data (RCD) to better inform consumers. In doing so, the Commission notes that these tools provide significant benefit to consumers, particularly in combination with an indication that caller ID has been authenticated. Although the Commission declined to regulate such tools at this time, it also stated that it “may consider a mandate in the future, particularly if the timely deployment of such valuable tools does not occur without Commission intervention.”
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Wiley’s Telecom, Media & Technology Practice has a deep and experienced robocalling bench, and our experts handle federal and state policy issues, compliance with federal and state requirements, and complex TCPA issues. For more information or assistance with complying with the new DNO blocking requirements, please contact one of the authors listed on this alert.
