“Delivered” at the API level means the message was accepted by the downstream carrier / aggregator, not that it necessarily reached the handset. In some regions and carriers, especially for A2P traffic, messages can be filtered or silently dropped after that point.
we’re actively working on:
clearer delivery state distinctions (accepted vs handset-delivered)
fallback routing where possible
better guidance on sender IDs and content patterns that reduce filtering
If you’re open to it, sharing the country, carrier, and message type (transactional vs promo) helps us dig deeper.