10DLC (10-digit long code) is the US carrier framework under which application traffic from standard 10-digit numbers must be registered per brand and campaign; unregistered A2P traffic is filtered.
Since 2021 the US carriers require senders of application traffic from ordinary long codes to register their brand and each campaign with The Campaign Registry, with vetting scores that set throughput. It replaced the grey area where marketing was sent from consumer-style numbers.
For a sender outside the US, the practical consequences are: no alphanumeric name, throughput tied to registration, and content filtered against the registered use case. Transactional traffic from a gateway's registered numbers still delivers; a foreign brand wanting its own registered campaign needs a US entity and the registration process.
At SMSMeteor: US traffic is sent from numeric senders on the platform's routes; the 10DLC guide explains what an international sender can and cannot expect.