Before 2021, anyone could buy a 10-digit phone number and send SMS at scale with no registration. Carriers shut that down to reduce spam. Now if you are a business sending automated texts, you must register two things: your brand (who you are) and your campaign (what kind of messages you send).
GoHighLevel uses LC Phone, its built-in phone system, to process SMS. LC Phone sits on top of Twilio. Both Twilio and the US carriers require A2P 10DLC registration before they will deliver business SMS reliably. Without registration, your messages get filtered or blocked.
Registration is a one-time process per sub-account. You submit your business name, EIN (tax ID), website, and a description of the messages you plan to send. The carrier review takes a few business days. Once approved, your 10-digit numbers are cleared to send at normal throughput.
How A2P 10DLC works
In GoHighLevel, you register for A2P 10DLC under the sub-account phone settings. You fill out the Brand registration form first, which identifies your business. Then you create a Campaign registration, which describes the type of messages you will send, such as customer care, marketing, or notifications.
After submission, GoHighLevel submits your registration to The Campaign Registry (TCR), which the US carriers use as the central clearinghouse. Once TCR and the carriers approve it, your registered numbers show a "verified" status and you can send business text messages on them.