For telemarketing and spam text messages that advertise a product or service, the requirement is that the sender obtains written consent (either physical or electronic).
Even if you are not selling anything, it’s helpful to have an opt out message in your text messages to a new number within the first ten days of reaching out to them.
I use something like:
“Miriam! We are still buying houses in your area. Have you considered selling 2134 Highland Ave? Type HELP to learn more.“
When they type HELP it shows our link and the STOP option to remove them from our list.
All of my messages are individually sent and there is nothing bulk or automated about their construction.
When they send STOP at any time my service Twilio immediately puts them on a do not send list for that number until they send a START message.
The fine is $500 per text you send after they ask you stop sending messages within a 10 day compliance window. The receiver and the receivers lawyer get paid the $500.
My political clients do not have to check with “Do Not Call” registry because they are exempt from this rule. The exemptions also include companies that are not trying to sell anything like survey companies. Also if your list is less than 2000 people (commercial enterprise rule) than you have some leeway with the courts as well. Regardless of exemptions you must stop sending messages once the receiver requests you to stop.