A petition signature is a signature on a petition, not a texting opt-in. If someone signed to support an issue and you later text their cell, that text is unsolicited unless the petition form clearly and conspicuously asked for consent to receive texts and they affirmatively agreed.
How to make a petition a real opt-in
Add a distinct, honest consent line to the petition: 'Text me updates about this campaign (msg & data rates may apply, reply STOP to cancel).' A checked box tied to that language gives you documented consent. The signature and the opt-in are two separate yeses.
Why it matters
Petition lists feel like warm contacts, so campaigns text them assuming consent travels with the signature. It doesn't, and texting signers who didn't opt in is the exact fact pattern that generates spam reports and TCPA claims.
Frequently asked questions
Is signing a petition consent to be texted?
No, not on its own. Consent requires the petition to clearly ask for text permission and the person to affirmatively agree. The act of signing doesn't carry a texting opt-in with it.
How do I collect text consent on a petition?
Add a separate, clearly worded opt-in checkbox with the required disclosures (who's texting, msg/data rates, reply STOP), and keep a record of who checked it and when.
Informational, not legal advice.
Keep reading: Voting isn't consent, neither is donating and Do campaigns need consent to text voters.