Recently, US regulators have started enforcing much stricter rules around spam and robocalls. This includes penalties of $2,500 per non-compliant call levied on the carrier. As part of this, US carriers have tightened their filters and are watching call behaviour much more closely.
In practice, this means that even legitimate business calls can sometimes get blocked if the traffic looks like spam from a carrier’s point of view.
Below we’ll explain what US carriers are looking at, and some simple habits you can adopt to keep your numbers in good standing.
ℹ️ What US carriers are looking at
When you call US numbers, carriers look at a few key patterns in your call traffic:
Answered vs unanswered calls
They want to see a healthy ratio, with more answered calls than unanswered ones over time. If you repeatedly call lots of numbers that never pick up, that starts to look like spam.Average call duration (ACD)
Very short calls across most of your traffic are a red flag. Your overall average doesn’t need to be 5 minutes long, but if most calls are just a few seconds, carriers may classify the traffic as suspicious. Generally, they want to see average calls above roughly 60–90 seconds.Percentage of very short calls
Calls that last only a few seconds (for example, ring–hang up, or instantly hanging up on voicemail) are a problem when they make up too big a percentage of your total calls.
If these patterns look “spammy” to US carriers, they’re more likely to start blocking calls from that number or route.
✅ Best practices to avoid getting blocked
Here are some practical steps you can take when calling US numbers:
1. Don’t repeatedly call numbers that don't answer
If someone doesn’t pick up the first time, avoid calling them again and again in a short period.
Instead:
Try once, maybe a second time later in the day or week.
If there’s still no answer, follow up via SMS/email rather than hammering the number with calls.
This keeps your unanswered/answered ratio healthier.
2. Let voicemail play out and leave a message
If your call goes to voicemail, don’t hang up after 2–3 seconds. That behaviour is exactly what carriers see from automated spam systems.
Instead:
Let the voicemail greeting play.
Leave a short, friendly message (who you are, why you’re calling, and how they can reach you).
This naturally increases your average call duration and reduces the percentage of ultra-short calls.
3. Avoid “power dialling” behaviour
Even if you’re not using a predictive dialler, patterns like:
Very short calls
Rapid-fire retries
Calling large lists that never pick up
…can still look like automated spam to US carriers. Slow things down slightly, be selective with who you call, and mix your outreach with SMS and email.
4. Keep things consistent once contact is made
Once a candidate or contact has spoken to you:
Try to keep calling from the same number, so they recognise you.
Ask them to save your number in their contacts when appropriate.
This improves pickup rates and reduces the chance of your calls being marked as spam or blocked on the device itself.
📚 Want to understand other reasons calls may not connect?
Smartphones also have additional spam and call-screening features that can send your calls straight to voicemail or hide them completely.
For a deeper dive into that (including iPhone and Android settings), check out this article:
My calls are going straight to voicemail or not connecting
By keeping an eye on how you call US numbers and adopting these simple habits, you’ll reduce the risk of your traffic being flagged and help ensure more of your legitimate calls reach the people you’re trying to speak to.
Sources
$4.5 million fine for US carrier that allowed spam and robo-calls on their platform: https://docs.fcc.gov/public/attachments/DOC-409354A1.pdf