SMS showing "delivered" but never received — Switzerland (Sunrise & Swisscom)

Hi ​@Beni , 
 

Thanks for the detailed write-up — this is really helpful context and you've done solid troubleshooting here.

You're right that "Carrier Delivery Status: Delivered" can be misleading in this situation. That status confirms the message left our platform and was acknowledged at the carrier gateway level, but it doesn't guarantee the message reached the handset. Swiss carriers (Swisscom, Sunrise, Salt) have their own filtering layer after that gateway acknowledgment, and they don't always report back when a message is silently dropped.

The pattern you're describing — delivered status on both Sunrise and Swisscom with zero handset receipt — is consistent with a carrier-level registration issue. Branded/alphanumeric sender IDs require formal registration with carrier partners in Switzerland, and the "active for CH" status in your sender settings reflects your account configuration, not confirmed carrier-side registration. Those two things aren't always the same.

I'm going to open a ticket for you so our SMS deliverability team can verify the carrier registration status of your sender ID specifically for Switzerland. They'll have visibility into whether the ID is provisioned with the Swiss carrier partners on the back end.

In the meantime, a couple of things worth checking:
- Confirm your test subscribers were collected via double opt-in — Swiss carriers prefer this and single opt-in can contribute to filtering
- Make sure your messages include an unsubscribe link (since alphanumeric IDs can't receive STOP keywords, a link is required)

Our team will follow up via the ticket with next steps. Thanks for your patience on this!