Posts tagged filtering.
Text only people who opted in, identify yourself, honor STOP instantly, register under 10DLC, and send messages people actually want. Spam filtering is driven by recipient behavior, so the fix is giving recipients nothing to report.
The usual culprits are missing or incomplete 10DLC registration, a weak sender reputation, content that trips spam filters, or sending to dead or unconsented numbers. Carriers filter silently, so 'sent' doesn't mean 'delivered.'
Sender reputation is the carriers' running judgment of whether your traffic is wanted, built from complaint rates, STOP rates, and spam reports. A good reputation delivers; a bad one gets filtered. It's earned over time and can't be bought back quickly.