Consent is an affirmative, documented yes to texts, not the absence of a no. The standard is prior express written consent: the person knowingly agreed to receive your messages at that number, saw what they were signing up for, and you can prove it. Everything short of that, assumptions, pre-checks, transferred lists, fails when tested.
What a valid opt-in looks like
A clear statement of who's texting and what they'll receive, an affirmative action by the person (checking an unchecked box, texting a keyword, submitting a form), notice of msg/data rates and the right to reply STOP, and a stored record with a timestamp. That record is what turns 'we had consent' from a claim into a defense.
What doesn't count
A pre-checked box, consent buried in unrelated terms, a number collected for a different purpose, a purchased list, or 'they're a supporter, surely they're fine with it.' None of these is affirmative, informed, documented agreement to texts, and each is a common way campaigns end up liable.
Frequently asked questions
What counts as consent to text someone?
Prior express written consent: a clear, affirmative, documented agreement to receive your texts at that number, with disclosure of what they'll get and the right to reply STOP. You must be able to prove it.
Does giving a campaign my number count as consent to text?
Not by itself. Consent must be affirmative and informed, an opt-in action with disclosures, not just a number collected for some other purpose. A purchased list or pre-checked box doesn't qualify.
Informational, not legal advice.
Keep reading: What is prior express written consent for texts and Can I buy a list of cell numbers to text.