April 1, 2026
Will the FCC’s SIP Code 603+ Mandate Enhance Call Remediation Efforts?
The STIR/SHAKEN framework uses Session Initiation Protocol (SIP) codes to indicate a broad range of actions. When it comes to blocked calls, carriers and analytics engines have used 607 and 608 SIP headers, but these are being phased out.
Things changed on March 25, 2026, when the FCC adopted SIP code 603+ to let businesses know when their calls are blocked. This change should simplify and modernize the exchange of call information between network providers using Rich Call Data (RCD). It also means that businesses will need to learn about the change and start using SIP code 603+ call remediation efforts.
While the transition might cause some short-term confusion for businesses, it should make the process much easier over time.
FCC Mandates Use of SIP 603+ Code
Starting March 25, 2026, the FCC will start requiring carriers and analytics engines to provide a SIP 603+ code when they flag or block calls. This effectively eliminates 603, 607, and 608 as options, which supports the FCC’s ongoing effort to establish uniform standards that help callers understand when and why outbound calls are blocked.
What Is the SIP 603+ Code?
SIP 603+ is very similar to the 603 SIP code used until recently. Unlike 603, though, 603+ specifically states that a call was “Network Blocked.” The SIP 603 code simply stated “Decline.” The SIP 603+ code also includes a SIP Reason header that businesses can use to understand why calls have been blocked. The 603+ SIP header also provides additional information about how the caller can redress any issues that prevent them from connecting with customers.
Phasing Out SIP 607/608 Codes
Phasing out SIP 607 and 608 will help every caller access the information they need for call remediation efforts. Both 607 and 608 provided information about why the call was declined and who declined it. Unfortunately, 607 and 608 weren’t universally supported throughout the industry. That meant that some businesses couldn’t understand why their calls were blocked.
The information provided by 607 and 608 SIP headers was also difficult for laypeople to understand, leading to confusion and uncertainty.
FCC Calls for a Standard Code 603+
With the implementation of Rich Call Data (RCD), SIP 603+ provides a detailed, uniform code that lets businesses know why carriers and analytics engines are blocking their calls.
If you see 603+, it means a carrier or analytics engine prevented your call from reaching its destination. STIR/SHAKEN still supports SIP 603, which means that the person you called declined to answer. This can happen if the person declines your call or blocks your number.
It’s important to know that you will only get a 603+ code when the carrier or an analytics engine blocks your call. It doesn’t have anything to do with the intended recipient. That means you will need to direct your SIP code 603+ call remediation efforts to the service provider that blocked the call.
How the SIP 603+ Code Benefits Businesses
The SIP 603+ code provides consistency and transparency that will benefit businesses. Imagine that you place a call that gets blocked. You’ll get a 603+ code that tells you who blocked the call. In most cases, you’ll also get information about why the call was blocked. Since SIP 603+ uses standardized codes, you won’t need to worry about getting carrier-specific codes. Instead of dealing with diverse codes from different companies, you will get uniform codes from a single source.
When you reach out to the provider that denied your connection, you will have the information you need to quickly remediate the issue. That means you can start connecting with leads, customers, and clients sooner than when carriers used multiple SIP codes.
Detailed RCD Information for Call Remediation
The move to 603+ will make it easier for companies to remediate blocked calls because each code will tell you :
- Which carrier, analytics engine, or other party blocked the call.
- Why the call was blocked.
- Who to contact about remediating the issue.
Now that you’ll have access to this information, you will know exactly why your call was blocked. You won’t need to rely on guesswork or indecipherable codes from numerous companies.
The next time your number gets inaccurately blocked for spam, robocalls, or scam efforts, you can handle the issue more efficiently and effectively than before.
Our Remediation Managed Services Simplifies This Process
That doesn’t necessarily mean that remediation will always be easy, though. That’s why Caller ID Reputation offers professional number redress and remediation services. STIR/SHAKEN requires carriers to respond to requests within 48 hours. With an experienced professional handling remediation, though, you can get quick results without wasting any time. That means you can start connecting with your customers, keeping them happier and more dedicated to your services and products.
