SIP 603 Blocked Calls: What Health Insurance Call Centers Need to Know About the FCC’s New 603+ Standard
Published: March 2026
Your agents are dialing. The calls aren’t connecting. And nobody knows why.
Sound familiar? If your team is running outbound call campaigns, there’s a good chance SIP 603 blocked calls are quietly eating into your contact rates — and as of March 25, 2026, the rules around how those blocks get reported have officially changed. Here’s what it means for your agency, in plain English.
First — What Is a SIP Code?
Every time your agent makes a call, the phone network sends back a little status update behind the scenes. These are called SIP codes (SIP stands for Session Initiation Protocol — the technology that runs VoIP calls). Think of them like the “read receipts” of your phone system. They tell you whether the call went through, got ignored, or got blocked — and why.
Most agencies never see these codes because they’re buried in call records that have to be pulled from your dialing platform. But they contain some of the most useful information available for understanding why your calls aren’t connecting. Three codes matter most right now: 603, 607, and 608.
Breaking Down the SIP 603 Blocked Calls Codes
SIP 603 — The call was rejected. The call made it to the other end, but someone — or something — said no. Maybe the recipient hit “Decline.” Maybe their phone has an auto-reject setting. Maybe a spam filter on their device blocked it. Either way, this isn’t a problem with your phone system — the call got there, it just wasn’t accepted. That said, if you’re seeing a lot of 603s on a particular number, it’s worth paying attention. It could mean your caller ID is getting screened or that someone on your list is on a Do Not Call registry that wasn’t filtered out.
SIP 607 — The person flagged your call as unwanted. This one’s more serious. A 607 means the recipient — or an app on their phone like Hiya or Truecaller — explicitly marked your number as spam or unwanted. That’s a direct hit to your caller ID reputation. If you start seeing 607s pile up on a number, that number needs to come out of rotation. Left unchecked, it’s a fast track to getting blocked at the carrier level entirely.
SIP 608 — The carrier blocked you. This is the big one. A 608 means the call never even had a chance — it was stopped by the phone carrier before it reached anyone. This can happen if your account has been flagged, if a specific number has been hard-blocked, or if there’s a route issue on your provider’s end. If you’re seeing 608s, don’t wait — contact your VoIP provider right away and give them the details from your call records.
So What’s New? Meet SIP 603+
The FCC recently added a new code to the mix: SIP 603+, which became mandatory on March 25, 2026. It’s specifically for calls that get blocked by a carrier’s spam detection system — before your call ever reaches the person you’re trying to reach.
The big upgrade here is transparency. The old 603 code just said “Declined” — no explanation, no trail to follow. The new 603+ says “Network Blocked” and includes information about which carrier blocked the call and how to contact them to dispute it. So if your legitimate enrollment calls are getting caught in a spam filter by mistake, you now have a clear path to get that fixed.
One important heads-up though: 603+ won’t catch everything. A lot of call blocking actually happens in the middle of the network — between carriers — before it even gets to the final destination. When that happens, your system often just sees a generic error code, not a 603+. So if your 603+ numbers look low, don’t assume blocking isn’t happening. It might just be showing up somewhere else in your data.
How TLD CRM Has You Covered
Because this stuff directly affects your ability to reach clients and prospects, we built dedicated tracking right into TLD. Under Telephony > CDR, you’ll find a report that monitors 603, 607, and 608 activity across all your call traffic — so you can actually see what’s happening instead of guessing.
We also take an active approach to protecting your numbers: when a number gets a 603 response, TLD automatically flags it. That means problem numbers get caught early — before they rack up a bad reputation with carriers or run into issues with the FCC’s new requirements. It’s part of how we keep your team dialing clean and compliant with our telecom partner, Telnyx.
What You Should Do Right Now
Check your CDR report in TLD. Make it a habit — not just something you look at when something feels off. Regular monitoring of your 603, 607, and 608 activity is the fastest way to catch problems early.
Don’t ignore 607s. A user flagging your number as spam is a warning shot. Pull that number, find out why it’s getting flagged, and fix it before it becomes a bigger problem.
Treat 608s as urgent. A carrier-level block needs immediate attention. Call your VoIP provider, share your call records, and get to the bottom of it fast.
Register your numbers. You can list your caller IDs with major carrier spam-detection systems through the Free Caller Registry — it’s free and reduces the chance of your legitimate calls getting mislabeled as spam.
Use the new 603+ dispute process. When you see a 603+ response, you now have the carrier’s contact information built into that code. Use it. That dispute path is brand new and it’s there for exactly this situation.
The agencies that stay on top of this data will protect their contact rates and keep their carrier relationships healthy. The ones that don’t will keep losing calls — and keep wondering why their numbers aren’t performing.
TLD CRM was built specifically for health and life insurance agencies. With TLDialer, dedicated CDR reporting for SIP 603, 607, and 608 tracking, and robust call performance analytics, your team has the tools to protect your outbound operation and stay ahead of FCC compliance requirements. Request a live demo today.
Sources
- Twilio — Say Hello to SIP Code 603+: The FCC’s New Standard for Analytics-based Blocked Calls (September 15, 2025)
https://www.twilio.com/en-us/blog/insights/fcc_new_standard - Zoiper — SIP 603 – Declined
https://www.zoiper.com/en/support/home/article/71/SIP%20603%20-%20Declined - Contact Center Compliance via LinkedIn Pulse — SIP Code 603+: The Transparency Promise vs. The Operational Reality (March 16, 2026)
https://www.linkedin.com/pulse/sip-code-603-transparency-promise-vs-operational-hhxkc/