10DLC
The US carriers' way of letting A2P texts ride on ordinary ten-digit local numbers — provided the business registers a brand and a campaign first.
10DLC stands for "10-digit long code": a plain local phone number cleared for A2P traffic. Before the scheme, automated texting went out either from expensive short codes or from regular numbers the carriers could silently block as spam at any moment — unpredictable for everyone involved.
Since 2021, AT&T, T-Mobile and Verizon require the sender to register with The Campaign Registry: one brand and each individual messaging campaign. The number then earns a throughput quota and a trust score. The upside is steadier delivery; the downside is fees, approval delays and a layer of bureaucracy that CPaaS firms like Twilio now handle on their customers' behalf.